org.apache.ant/ant/1.10.7 : org/apache/tools/ant/taskdefs/optional/extension/Extension.java

Extension
https://ant.apache.org/: master POM (The Apache Software Foundation)
The Apache Software License, Version 2.0
/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 */
package org.apache.tools.ant.taskdefs.optional.extension;

import java.util.ArrayList;
import java.util.List;
import java.util.Objects;
import java.util.Optional;
import java.util.StringTokenizer;
import java.util.jar.Attributes;
import java.util.jar.Manifest;
import java.util.stream.Stream;

import org.apache.tools.ant.util.DeweyDecimal;

Utility class that represents either an available "Optional Package"
(formerly known as "Standard Extension") as described in the manifest
of a JAR file, or the requirement for such an optional package.
For more information about optional packages, see the document
Optional Package Versioning in the documentation bundle for your
Java2 Standard Edition package, in file
guide/extensions/versioning.html.
/**
 * <p>Utility class that represents either an available "Optional Package"
 * (formerly known as "Standard Extension") as described in the manifest
 * of a JAR file, or the requirement for such an optional package.</p>
 *
 * <p>For more information about optional packages, see the document
 * <em>Optional Package Versioning</em> in the documentation bundle for your
 * Java2 Standard Edition package, in file
 * <code>guide/extensions/versioning.html</code>.</p>
 *
 */
public final class Extension {
    Manifest Attribute Name object for EXTENSION_LIST.
/**
     * Manifest Attribute Name object for EXTENSION_LIST.
     */
    public static final Attributes.Name EXTENSION_LIST
        = new Attributes.Name("Extension-List");

    Name object for Optional-Extension-List
manifest attribute used for declaring optional dependencies on
installed extensions. Note that the dependencies declared by this method
are not required for the library to operate but if present will be used.
It is NOT part of the official "Optional Package" specification.
See Also: 
     *      Installed extension dependency/**
     * <code>Name</code> object for <code>Optional-Extension-List</code>
     * manifest attribute used for declaring optional dependencies on
     * installed extensions. Note that the dependencies declared by this method
     * are not required for the library to operate but if present will be used.
     * It is NOT part of the official "Optional Package" specification.
     *
     * @see <a href="https://docs.oracle.com/javase/8/docs/technotes/guides/extensions/spec.html#dependency">
     *      Installed extension dependency</a>
     */
    public static final Attributes.Name OPTIONAL_EXTENSION_LIST
        = new Attributes.Name("Optional-Extension-List");

    Manifest Attribute Name object for EXTENSION_NAME.
/**
     * Manifest Attribute Name object for EXTENSION_NAME.
     */
    public static final Attributes.Name EXTENSION_NAME =
        new Attributes.Name("Extension-Name");
    Manifest Attribute Name object for SPECIFICATION_VERSION.
/**
     * Manifest Attribute Name object for SPECIFICATION_VERSION.
     */
    public static final Attributes.Name SPECIFICATION_VERSION
        = Attributes.Name.SPECIFICATION_VERSION;

    Manifest Attribute Name object for SPECIFICATION_VENDOR.
/**
     * Manifest Attribute Name object for SPECIFICATION_VENDOR.
     */
    public static final Attributes.Name SPECIFICATION_VENDOR
        = Attributes.Name.SPECIFICATION_VENDOR;

    Manifest Attribute Name object for IMPLEMENTATION_VERSION.
/**
     * Manifest Attribute Name object for IMPLEMENTATION_VERSION.
     */
    public static final Attributes.Name IMPLEMENTATION_VERSION
        = Attributes.Name.IMPLEMENTATION_VERSION;

    Manifest Attribute Name object for IMPLEMENTATION_VENDOR.
/**
     * Manifest Attribute Name object for IMPLEMENTATION_VENDOR.
     */
    public static final Attributes.Name IMPLEMENTATION_VENDOR
        = Attributes.Name.IMPLEMENTATION_VENDOR;

    Manifest Attribute Name object for IMPLEMENTATION_URL.
/**
     * Manifest Attribute Name object for IMPLEMENTATION_URL.
     */
    public static final Attributes.Name IMPLEMENTATION_URL
        = new Attributes.Name("Implementation-URL");

    Manifest Attribute Name object for IMPLEMENTATION_VENDOR_ID.
/**
     * Manifest Attribute Name object for IMPLEMENTATION_VENDOR_ID.
     */
    public static final Attributes.Name IMPLEMENTATION_VENDOR_ID
        = new Attributes.Name("Implementation-Vendor-Id");

    Enum indicating that extension is compatible with other extension.
/**
     * Enum indicating that extension is compatible with other extension.
     */
    public static final Compatibility COMPATIBLE
        = new Compatibility("COMPATIBLE");

    Enum indicating that extension requires an upgrade
of specification to be compatible with other extension.
/**
     * Enum indicating that extension requires an upgrade
     * of specification to be compatible with other extension.
     */
    public static final Compatibility REQUIRE_SPECIFICATION_UPGRADE
        = new Compatibility("REQUIRE_SPECIFICATION_UPGRADE");

    Enum indicating that extension requires a vendor
switch to be compatible with other extension.
/**
     * Enum indicating that extension requires a vendor
     * switch to be compatible with other extension.
     */
    public static final Compatibility REQUIRE_VENDOR_SWITCH
        = new Compatibility("REQUIRE_VENDOR_SWITCH");

    Enum indicating that extension requires an upgrade
of implementation to be compatible with other extension.
/**
     * Enum indicating that extension requires an upgrade
     * of implementation to be compatible with other extension.
     */
    public static final Compatibility REQUIRE_IMPLEMENTATION_UPGRADE
        = new Compatibility("REQUIRE_IMPLEMENTATION_UPGRADE");

    Enum indicating that extension is incompatible with
other extension in ways other than other enums
indicate). For example the other extension may have
a different ID.
/**
     * Enum indicating that extension is incompatible with
     * other extension in ways other than other enums
     * indicate). For example the other extension may have
     * a different ID.
     */
    public static final Compatibility INCOMPATIBLE
        = new Compatibility("INCOMPATIBLE");

    The name of the optional package being made available, or required.
/**
     * The name of the optional package being made available, or required.
     */
    private String extensionName;

    The version number (dotted decimal notation) of the specification
to which this optional package conforms.
/**
     * The version number (dotted decimal notation) of the specification
     * to which this optional package conforms.
     */
    private DeweyDecimal specificationVersion;

    The name of the company or organization that originated the
specification to which this optional package conforms.
/**
     * The name of the company or organization that originated the
     * specification to which this optional package conforms.
     */
    private String specificationVendor;

    The unique identifier of the company that produced the optional
package contained in this JAR file.
/**
     * The unique identifier of the company that produced the optional
     * package contained in this JAR file.
     */
    private String implementationVendorID;

    The name of the company or organization that produced this
implementation of this optional package.
/**
     * The name of the company or organization that produced this
     * implementation of this optional package.
     */
    private String implementationVendor;

    The version number (dotted decimal notation) for this implementation
of the optional package.
/**
     * The version number (dotted decimal notation) for this implementation
     * of the optional package.
     */
    private DeweyDecimal implementationVersion;

    The URL from which the most recent version of this optional package
can be obtained if it is not already installed.
/**
     * The URL from which the most recent version of this optional package
     * can be obtained if it is not already installed.
     */
    private String implementationURL;

    Return an array of Extension objects representing optional
packages that are available in the JAR file associated with the
specified Manifest.  If there are no such optional
packages, a zero-length array is returned.
Params: manifest – Manifest to be parsed
Returns: the "available" extensions in specified manifest/**
     * Return an array of <code>Extension</code> objects representing optional
     * packages that are available in the JAR file associated with the
     * specified <code>Manifest</code>.  If there are no such optional
     * packages, a zero-length array is returned.
     *
     * @param manifest Manifest to be parsed
     * @return the "available" extensions in specified manifest
     */
    public static Extension[] getAvailable(final Manifest manifest) {
        if (null == manifest) {
            return new Extension[0];
        }
        return Stream
            .concat(Optional.ofNullable(manifest.getMainAttributes())
                    .map(Stream::of).orElse(Stream.empty()),
                manifest.getEntries().values().stream())
            .map(attrs -> getExtension("", attrs)).filter(Objects::nonNull)
            .toArray(Extension[]::new);
    }

    Return the set of Extension objects representing optional
packages that are required by the application contained in the JAR
file associated with the specified Manifest.  If there
are no such optional packages, a zero-length list is returned.
Params: manifest – Manifest to be parsed
Returns: the dependencies that are specified in manifest/**
     * Return the set of <code>Extension</code> objects representing optional
     * packages that are required by the application contained in the JAR
     * file associated with the specified <code>Manifest</code>.  If there
     * are no such optional packages, a zero-length list is returned.
     *
     * @param manifest Manifest to be parsed
     * @return the dependencies that are specified in manifest
     */
    public static Extension[] getRequired(final Manifest manifest) {
        return getListed(manifest, Attributes.Name.EXTENSION_LIST);
    }

    Return the set of Extension objects representing "Optional
Packages" that the application declares they will use if present. If
there are no such optional packages, a zero-length list is returned.
Params: manifest – Manifest to be parsed
Returns: the optional dependencies that are specified in manifest/**
     * Return the set of <code>Extension</code> objects representing "Optional
     * Packages" that the application declares they will use if present. If
     * there are no such optional packages, a zero-length list is returned.
     *
     * @param manifest Manifest to be parsed
     * @return the optional dependencies that are specified in manifest
     */
    public static Extension[] getOptions(final Manifest manifest) {
        return getListed(manifest, OPTIONAL_EXTENSION_LIST);
    }

    Add Extension to the specified manifest Attributes.
Params: attributes – the attributes of manifest to add to
extension – the extension/**
     * Add Extension to the specified manifest Attributes.
     *
     * @param attributes the attributes of manifest to add to
     * @param extension the extension
     */
    public static void addExtension(final Extension extension,
                                     final Attributes attributes) {
        addExtension(extension, "", attributes);
    }

    Add Extension to the specified manifest Attributes.
Use the specified prefix so that dependencies can added
with a prefix such as "java3d-" etc.
Params: attributes – the attributes of manifest to add to
extension – the extension
prefix – the name to prefix to extension/**
     * Add Extension to the specified manifest Attributes.
     * Use the specified prefix so that dependencies can added
     * with a prefix such as "java3d-" etc.
     *
     * @param attributes the attributes of manifest to add to
     * @param extension the extension
     * @param prefix the name to prefix to extension
     */
    public static void addExtension(final Extension extension,
                                     final String prefix,
                                     final Attributes attributes) {
        attributes.putValue(prefix + EXTENSION_NAME,
                             extension.getExtensionName());

        final String specificationVendor = extension.getSpecificationVendor();
        if (null != specificationVendor) {
            attributes.putValue(prefix + SPECIFICATION_VENDOR,
                                 specificationVendor);
        }

        final DeweyDecimal specificationVersion
            = extension.getSpecificationVersion();
        if (null != specificationVersion) {
            attributes.putValue(prefix + SPECIFICATION_VERSION,
                                 specificationVersion.toString());
        }

        final String implementationVendorID
            = extension.getImplementationVendorID();
        if (null != implementationVendorID) {
            attributes.putValue(prefix + IMPLEMENTATION_VENDOR_ID,
                                 implementationVendorID);
        }

        final String implementationVendor = extension.getImplementationVendor();
        if (null != implementationVendor) {
            attributes.putValue(prefix + IMPLEMENTATION_VENDOR,
                                 implementationVendor);
        }

        final DeweyDecimal implementationVersion
            = extension.getImplementationVersion();
        if (null != implementationVersion) {
            attributes.putValue(prefix + IMPLEMENTATION_VERSION,
                                 implementationVersion.toString());
        }

        final String implementationURL = extension.getImplementationURL();
        if (null != implementationURL) {
            attributes.putValue(prefix + IMPLEMENTATION_URL,
                                 implementationURL);
        }
    }

    The constructor to create Extension object.
Note that every component is allowed to be specified
but only the extensionName is mandatory.
Params: extensionName – the name of extension.
specificationVersion – the specification Version of extension.
specificationVendor – the specification Vendor of extension.
implementationVersion – the implementation Version of extension.
implementationVendor – the implementation Vendor of extension.
implementationVendorId – the implementation VendorId of extension.
implementationURL – the implementation URL of extension./**
     * The constructor to create Extension object.
     * Note that every component is allowed to be specified
     * but only the extensionName is mandatory.
     *
     * @param extensionName the name of extension.
     * @param specificationVersion the specification Version of extension.
     * @param specificationVendor the specification Vendor of extension.
     * @param implementationVersion the implementation Version of extension.
     * @param implementationVendor the implementation Vendor of extension.
     * @param implementationVendorId the implementation VendorId of extension.
     * @param implementationURL the implementation URL of extension.
     */
    public Extension(final String extensionName,
                      final String specificationVersion,
                      final String specificationVendor,
                      final String implementationVersion,
                      final String implementationVendor,
                      final String implementationVendorId,
                      final String implementationURL) {
        this.extensionName = extensionName;
        this.specificationVendor = specificationVendor;

        if (null != specificationVersion) {
            try {
                this.specificationVersion
                    = new DeweyDecimal(specificationVersion);
            } catch (final NumberFormatException nfe) {
                final String error = "Bad specification version format '"
                    + specificationVersion + "' in '" + extensionName
                    + "'. (Reason: " + nfe + ")";
                throw new IllegalArgumentException(error);
            }
        }

        this.implementationURL = implementationURL;
        this.implementationVendor = implementationVendor;
        this.implementationVendorID = implementationVendorId;

        if (null != implementationVersion) {
            try {
                this.implementationVersion
                    = new DeweyDecimal(implementationVersion);
            } catch (final NumberFormatException nfe) {
                final String error = "Bad implementation version format '"
                    + implementationVersion + "' in '" + extensionName
                    + "'. (Reason: " + nfe + ")";
                throw new IllegalArgumentException(error);
            }
        }

        if (null == this.extensionName) {
            throw new NullPointerException("extensionName property is null");
        }
    }

    Get the name of the extension.
Returns: the name of the extension/**
     * Get the name of the extension.
     *
     * @return the name of the extension
     */
    public String getExtensionName() {
        return extensionName;
    }

    Get the vendor of the extensions specification.
Returns: the vendor of the extensions specification./**
     * Get the vendor of the extensions specification.
     *
     * @return the vendor of the extensions specification.
     */
    public String getSpecificationVendor() {
        return specificationVendor;
    }

    Get the version of the extensions specification.
Returns: the version of the extensions specification./**
     * Get the version of the extensions specification.
     *
     * @return the version of the extensions specification.
     */
    public DeweyDecimal getSpecificationVersion() {
        return specificationVersion;
    }

    Get the url of the extensions implementation.
Returns: the url of the extensions implementation./**
     * Get the url of the extensions implementation.
     *
     * @return the url of the extensions implementation.
     */
    public String getImplementationURL() {
        return implementationURL;
    }

    Get the vendor of the extensions implementation.
Returns: the vendor of the extensions implementation./**
     * Get the vendor of the extensions implementation.
     *
     * @return the vendor of the extensions implementation.
     */
    public String getImplementationVendor() {
        return implementationVendor;
    }

    Get the vendorID of the extensions implementation.
Returns: the vendorID of the extensions implementation./**
     * Get the vendorID of the extensions implementation.
     *
     * @return the vendorID of the extensions implementation.
     */
    public String getImplementationVendorID() {
        return implementationVendorID;
    }

    Get the version of the extensions implementation.
Returns: the version of the extensions implementation./**
     * Get the version of the extensions implementation.
     *
     * @return the version of the extensions implementation.
     */
    public DeweyDecimal getImplementationVersion() {
        return implementationVersion;
    }

    Return a Compatibility enum indicating the relationship of this
Extension with the specified Extension.
Params: required – Description of the required optional package
Returns: the enum indicating the compatibility (or lack thereof)
        of specified extension/**
     * Return a Compatibility enum indicating the relationship of this
     * <code>Extension</code> with the specified <code>Extension</code>.
     *
     * @param required Description of the required optional package
     * @return the enum indicating the compatibility (or lack thereof)
     *         of specified extension
     */
    public Compatibility getCompatibilityWith(final Extension required) {
        // Extension Name must match
        if (!extensionName.equals(required.getExtensionName())) {
            return INCOMPATIBLE;
        }

        // Available specification version must be >= required
        final DeweyDecimal requiredSpecificationVersion
            = required.getSpecificationVersion();
        if (null != requiredSpecificationVersion) {
            if (null == specificationVersion
                || !isCompatible(specificationVersion, requiredSpecificationVersion)) {
                return REQUIRE_SPECIFICATION_UPGRADE;
            }
        }

        // Implementation Vendor ID must match
        final String requiredImplementationVendorID
            = required.getImplementationVendorID();
        if (null != requiredImplementationVendorID) {
            if (null == implementationVendorID
                || !implementationVendorID.equals(requiredImplementationVendorID)) {
                return REQUIRE_VENDOR_SWITCH;
            }
        }

        // Implementation version must be >= required
        final DeweyDecimal requiredImplementationVersion
            = required.getImplementationVersion();
        if (null != requiredImplementationVersion) {
            if (null == implementationVersion
                || !isCompatible(implementationVersion, requiredImplementationVersion)) {
                return REQUIRE_IMPLEMENTATION_UPGRADE;
            }
        }

        // This available optional package satisfies the requirements
        return COMPATIBLE;
    }

    Return true if the specified Extension
(which represents an optional package required by an application)
is satisfied by this Extension (which represents an
optional package that is already installed.  Otherwise, return
false.
Params: required – Description of the required optional package
Returns: true if the specified extension is compatible with this extension/**
     * Return <code>true</code> if the specified <code>Extension</code>
     * (which represents an optional package required by an application)
     * is satisfied by this <code>Extension</code> (which represents an
     * optional package that is already installed.  Otherwise, return
     * <code>false</code>.
     *
     * @param required Description of the required optional package
     * @return true if the specified extension is compatible with this extension
     */
    public boolean isCompatibleWith(final Extension required) {
        return (COMPATIBLE == getCompatibilityWith(required));
    }

    Return a String representation of this object.
Returns: string representation of object./**
     * Return a String representation of this object.
     *
     * @return string representation of object.
     */
    @Override
    public String toString() {
        final String format = "%s: %s%n";

        final StringBuilder sb = new StringBuilder(String.format(format,
                EXTENSION_NAME, extensionName));

        if (null != specificationVersion) {
            sb.append(String.format(format, SPECIFICATION_VERSION, specificationVersion));
        }

        if (null != specificationVendor) {
            sb.append(String.format(format, SPECIFICATION_VENDOR, specificationVendor));
        }

        if (null != implementationVersion) {
            sb.append(String.format(format, IMPLEMENTATION_VERSION, implementationVersion));
        }

        if (null != implementationVendorID) {
            sb.append(String.format(format, IMPLEMENTATION_VENDOR_ID, implementationVendorID));
        }

        if (null != implementationVendor) {
            sb.append(String.format(format, IMPLEMENTATION_VENDOR, implementationVendor));
        }

        if (null != implementationURL) {
            sb.append(String.format(format, IMPLEMENTATION_URL, implementationURL));
        }

        return sb.toString();
    }

    Return true if the first version number is greater than
or equal to the second; otherwise return false.
Params: first – First version number (dotted decimal)
second – Second version number (dotted decimal)/**
     * Return <code>true</code> if the first version number is greater than
     * or equal to the second; otherwise return <code>false</code>.
     *
     * @param first First version number (dotted decimal)
     * @param second Second version number (dotted decimal)
     */
    private boolean isCompatible(final DeweyDecimal first,
                                 final DeweyDecimal second) {
        return first.isGreaterThanOrEqual(second);
    }

    Retrieve all the extensions listed under a particular key
(Usually EXTENSION_LIST or OPTIONAL_EXTENSION_LIST).
Params: manifest – the manifest to extract extensions from
listKey – the key used to get list (Usually
       EXTENSION_LIST or OPTIONAL_EXTENSION_LIST)
Returns: the list of listed extensions/**
     * Retrieve all the extensions listed under a particular key
     * (Usually EXTENSION_LIST or OPTIONAL_EXTENSION_LIST).
     *
     * @param manifest the manifest to extract extensions from
     * @param listKey the key used to get list (Usually
     *        EXTENSION_LIST or OPTIONAL_EXTENSION_LIST)
     * @return the list of listed extensions
     */
    private static Extension[] getListed(final Manifest manifest,
                                          final Attributes.Name listKey) {
        final List<Extension> results = new ArrayList<>();
        final Attributes mainAttributes = manifest.getMainAttributes();

        if (null != mainAttributes) {
            getExtension(mainAttributes, results, listKey);
        }

        manifest.getEntries().values()
            .forEach(attributes -> getExtension(attributes, results, listKey));

        return results.toArray(new Extension[results.size()]);
    }

    Add required optional packages defined in the specified
attributes entry, if any.
Params: attributes – Attributes to be parsed
required – list to add required optional packages to
listKey – the key to use to lookup list, usually EXTENSION_LIST
   or OPTIONAL_EXTENSION_LIST/**
     * Add required optional packages defined in the specified
     * attributes entry, if any.
     *
     * @param attributes Attributes to be parsed
     * @param required list to add required optional packages to
     * @param listKey the key to use to lookup list, usually EXTENSION_LIST
     *    or OPTIONAL_EXTENSION_LIST
     */
    private static void getExtension(final Attributes attributes,
                                     final List<Extension> required,
                                     final Attributes.Name listKey) {
        final String names = attributes.getValue(listKey);
        if (null == names) {
            return;
        }
        for (final String prefix : split(names, " ")) {
            final Extension extension = getExtension(prefix + "-", attributes);
            if (null != extension) {
                required.add(extension);
            }
        }
    }

    Splits the string on every token into an array of strings.
Params: string – the string
onToken – the token
Returns: the resultant array/**
     * Splits the string on every token into an array of strings.
     *
     * @param string the string
     * @param onToken the token
     * @return the resultant array
     */
    private static String[] split(final String string,
                                        final String onToken) {
        final StringTokenizer tokenizer = new StringTokenizer(string, onToken);
        final String[] result = new String[tokenizer.countTokens()];

        for (int i = 0; i < result.length; i++) {
            result[i] = tokenizer.nextToken();
        }

        return result;
    }

    Extract an Extension from Attributes.
Prefix indicates the prefix checked for each string.
Usually the prefix is "<extension>-" if looking for a
Required extension. If you are looking for an
Available extension
then the prefix is "".
Params: prefix – the prefix for each attribute name
attributes – Attributes to searched
Returns: the new Extension object, or null/**
     * Extract an Extension from Attributes.
     * Prefix indicates the prefix checked for each string.
     * Usually the prefix is <em>"&lt;extension&gt;-"</em> if looking for a
     * <b>Required</b> extension. If you are looking for an
     * <b>Available</b> extension
     * then the prefix is <em>""</em>.
     *
     * @param prefix the prefix for each attribute name
     * @param attributes Attributes to searched
     * @return the new Extension object, or null
     */
    private static Extension getExtension(final String prefix,
                                          final Attributes attributes) {
        //WARNING: We trim the values of all the attributes because
        //Some extension declarations are badly defined (ie have spaces
        //after version or vendorID)
        final String nameKey = prefix + EXTENSION_NAME;
        final String name = getTrimmedString(attributes.getValue(nameKey));
        if (null == name) {
            return null;
        }

        final String specVendorKey = prefix + SPECIFICATION_VENDOR;
        final String specVendor
            = getTrimmedString(attributes.getValue(specVendorKey));
        final String specVersionKey = prefix + SPECIFICATION_VERSION;
        final String specVersion
            = getTrimmedString(attributes.getValue(specVersionKey));

        final String impVersionKey = prefix + IMPLEMENTATION_VERSION;
        final String impVersion
            = getTrimmedString(attributes.getValue(impVersionKey));
        final String impVendorKey = prefix + IMPLEMENTATION_VENDOR;
        final String impVendor
            = getTrimmedString(attributes.getValue(impVendorKey));
        final String impVendorIDKey = prefix + IMPLEMENTATION_VENDOR_ID;
        final String impVendorId
            = getTrimmedString(attributes.getValue(impVendorIDKey));
        final String impURLKey = prefix + IMPLEMENTATION_URL;
        final String impURL = getTrimmedString(attributes.getValue(impURLKey));

        return new Extension(name, specVersion, specVendor, impVersion,
                              impVendor, impVendorId, impURL);
    }

    Trim the supplied string if the string is non-null
Params: value – the string to trim or null
Returns: the trimmed string or null/**
     * Trim the supplied string if the string is non-null
     *
     * @param value the string to trim or null
     * @return the trimmed string or null
     */
    private static String getTrimmedString(final String value) {
        return null == value ? null : value.trim();
    }
}
Params:	manifest – Manifest to be parsed
Returns:	the "available" extensions in specified manifest
Params:	required – Description of the required optional package
Returns:	the enum indicating the compatibility (or lack thereof) of specified extension
Params:	manifest – the manifest to extract extensions from listKey – the key used to get list (Usually EXTENSION_LIST or OPTIONAL_EXTENSION_LIST)
Returns:	the list of listed extensions
Params:	string – the string onToken – the token
Returns:	the resultant array
Params:	prefix – the prefix for each attribute name attributes – Attributes to searched
Returns:	the new Extension object, or null
Params:	value – the string to trim or null
Returns:	the trimmed string or null
/

org.apache.ant/ ant/ 1.10.7/ org/apache/tools/ant/taskdefs/optional/extension/Extension.java
