https://developers.google.com/protocol-buffers/protobuf-java/: Core Protocol Buffers library. Protocol Buffers are a way of encoding structured data in an efficient yet extensible format. 
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package com.google.protobuf;


Interface for an RPC callback, normally called when an RPC completes. ParameterType is normally the method's response message type. 
Starting with version 2.3.0, RPC implementations should not try to build on this, but should
instead provide code generator plugins which generate code specific to the particular RPC
implementation. This way the generated code can be more appropriate for the implementation in use
and can avoid unnecessary layers of indirection.

Author:kenton@google.com Kenton Varda
/**
 * Interface for an RPC callback, normally called when an RPC completes. {@code ParameterType} is
 * normally the method's response message type.
 *
 * <p>Starting with version 2.3.0, RPC implementations should not try to build on this, but should
 * instead provide code generator plugins which generate code specific to the particular RPC
 * implementation. This way the generated code can be more appropriate for the implementation in use
 * and can avoid unnecessary layers of indirection.
 *
 * @author kenton@google.com Kenton Varda
 */
public interface RpcCallback<ParameterType> {
  void run(ParameterType parameter);
}