/*
 * Copyright (c) 2007, 2018 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Distribution License v. 1.0, which is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

package org.glassfish.gmbal;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Inherited;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

This is taken directly from JDK 7 in order to support this feature in
JDK 5.
Annotation that adds fields to a Descriptor.  This can be the
Descriptor for an MBean, or for an attribute, operation, or constructor
in an MBean, or for a parameter of an operation or constructor.
Consider this Standard MBean interface, for example:
public interface CacheControlMBean {
    @DescriptorFields("units=bytes")
    public long getCacheSize();
}

When a Standard MBean is made using this interface, the usual rules mean that it will have an attribute called CacheSize of type long. The DescriptorFields annotation will ensure that the MBeanAttributeInfo for this attribute will have a Descriptor that has a field called units with corresponding value bytes.
Similarly, if the interface looks like this:
public interface CacheControlMBean {
    @DescriptorFields({"units=bytes", "since=1.5"})
    public long getCacheSize();
}

then the resulting Descriptor will contain the following fields:

Name
Value
units
"bytes"
since
"1.5"

The @DescriptorFields annotation can be applied to:

a Standard MBean or MXBean interface;
a method in such an interface;
a parameter of a method in a Standard MBean or MXBean interface
when that method is an operation (not a getter or setter for an attribute);
a public constructor in the class that implements a Standard MBean
or MXBean;
a parameter in such a constructor.

Other uses of the annotation will either fail to compile or be
ignored.
Interface annotations are checked only on the exact interface that defines the management interface of a Standard MBean or an MXBean, not on its parent interfaces. Method annotations are checked only in the most specific interface in which the method appears; in other words, if a child interface overrides a method from a parent interface, only @DescriptorFields annotations in the method in the child interface are considered. 
The Descriptor fields contributed in this way must be consistent
with each other and with any fields contributed by
DescriptorKey annotations.  That is, two
different annotations, or two members of the same annotation, must
not define a different value for the same Descriptor field.  Fields
from annotations on a getter method must also be consistent with
fields from annotations on the corresponding setter method.
The Descriptor resulting from these annotations will be merged
with any Descriptor fields provided by the implementation, such as
the 
immutableInfo field for an MBean.  The fields from the annotations
must be consistent with these fields provided by the implementation.
@DescriptorFields and @DescriptorKey
The DescriptorKey annotation provides
another way to use annotations to define Descriptor fields.
@DescriptorKey requires more work but is also more
robust, because there is less risk of mistakes such as misspelling
the name of the field or giving an invalid value.
@DescriptorFields is more convenient but includes
those risks.  @DescriptorFields is more
appropriate for occasional use, but for a Descriptor field that you
add in many places, you should consider a purpose-built annotation
using @DescriptorKey.
Since:
1.7/** This is taken directly from JDK 7 in order to support this feature in
 * JDK 5.
 *
 * <p>Annotation that adds fields to a Descriptor.  This can be the
 * Descriptor for an MBean, or for an attribute, operation, or constructor
 * in an MBean, or for a parameter of an operation or constructor.</p>
 *
 * <p>Consider this Standard MBean interface, for example:</p>
 *
 * <pre>
 * public interface CacheControlMBean {
 *     <b>&#64;DescriptorFields("units=bytes")</b>
 *     public long getCacheSize();
 * }
 * </pre>
 *
 * <p>When a Standard MBean is made using this interface, the usual rules
 * mean that it will have an attribute called {@code CacheSize} of type
 * {@code long}.  The {@code DescriptorFields} annotation will ensure
 * that the MBeanAttributeInfo for this attribute will have a
 * {@code Descriptor} that has a field called {@code units} with
 * corresponding value {@code bytes}.</p>
 *
 * <p>Similarly, if the interface looks like this:</p>
 *
 * <pre>
 * public interface CacheControlMBean {
 *     <b>&#64;DescriptorFields({"units=bytes", "since=1.5"})</b>
 *     public long getCacheSize();
 * }
 * </pre>
 *
 * <p>then the resulting {@code Descriptor} will contain the following
 * fields:</p>
 *
 * <table border="2">
 * <tr><th>Name</th><th>Value</th></tr>
 * <tr><td>units</td><td>"bytes"</td></tr>
 * <tr><td>since</td><td>"1.5"</td></tr>
 * </table>
 *
 * <p>The {@code @DescriptorFields} annotation can be applied to:</p>
 *
 * <ul>
 * <li>a Standard MBean or MXBean interface;
 * <li>a method in such an interface;
 * <li>a parameter of a method in a Standard MBean or MXBean interface
 * when that method is an operation (not a getter or setter for an attribute);
 * <li>a public constructor in the class that implements a Standard MBean
 * or MXBean;
 * <li>a parameter in such a constructor.
 * </ul>
 *
 * <p>Other uses of the annotation will either fail to compile or be
 * ignored.</p>
 *
 * <p>Interface annotations are checked only on the exact interface
 * that defines the management interface of a Standard MBean or an
 * MXBean, not on its parent interfaces.  Method annotations are
 * checked only in the most specific interface in which the method
 * appears; in other words, if a child interface overrides a method
 * from a parent interface, only {@code @DescriptorFields} annotations in
 * the method in the child interface are considered.
 *
 * <p>The Descriptor fields contributed in this way must be consistent
 * with each other and with any fields contributed by
 * DescriptorKey annotations.  That is, two
 * different annotations, or two members of the same annotation, must
 * not define a different value for the same Descriptor field.  Fields
 * from annotations on a getter method must also be consistent with
 * fields from annotations on the corresponding setter method.</p>
 *
 * <p>The Descriptor resulting from these annotations will be merged
 * with any Descriptor fields provided by the implementation, such as
 * the <a href="Descriptor.html#immutableInfo">{@code
 * immutableInfo}</a> field for an MBean.  The fields from the annotations
 * must be consistent with these fields provided by the implementation.</p>
 *
 * <h4>{@literal @DescriptorFields and @DescriptorKey}</h4>
 *
 * <p>The DescriptorKey annotation provides
 * another way to use annotations to define Descriptor fields.
 * <code>&#64;DescriptorKey</code> requires more work but is also more
 * robust, because there is less risk of mistakes such as misspelling
 * the name of the field or giving an invalid value.
 * <code>&#64;DescriptorFields</code> is more convenient but includes
 * those risks.  <code>&#64;DescriptorFields</code> is more
 * appropriate for occasional use, but for a Descriptor field that you
 * add in many places, you should consider a purpose-built annotation
 * using <code>&#64;DescriptorKey</code>.
 *
 * @since 1.7
 */
@Documented
@Inherited  // for @MBean and @MXBean classes
@Target({ElementType.CONSTRUCTOR, ElementType.METHOD, ElementType.FIELD,
         ElementType.PARAMETER, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
public @interface DescriptorFields {
    
The descriptor fields. Each element of the string looks like "name=value".
/**
     * <p>The descriptor fields.  Each element of the string looks like
     * {@code "name=value"}.</p>
     */
    public String[] value();
}