HADOOP-7773 introduced 7 new findbugs warnings

Code Warning
Se com.google.protobuf.ByteString stored into non-transient field HadoopRpcProtos$HadoopRpcExceptionProto.exceptionName_
Se com.google.protobuf.ByteString stored into non-transient field HadoopRpcProtos$HadoopRpcExceptionProto.stackTrace_
Se Class org.apache.hadoop.ipc.protobuf.HadoopRpcProtos$HadoopRpcRequestProto defines non-transient non-serializable instance field request_
Se com.google.protobuf.ByteString stored into non-transient field HadoopRpcProtos$HadoopRpcRequestProto.methodName_
Se Class org.apache.hadoop.ipc.protobuf.HadoopRpcProtos$HadoopRpcResponseProto defines non-transient non-serializable instance field response_

Dodgy Warnings

Code Warning
UCF Useless control flow in org.apache.hadoop.ipc.protobuf.HadoopRpcProtos$HadoopRpcExceptionProto$Builder.maybeForceBuilderInitialization()
UCF Useless control flow in org.apache.hadoop.ipc.protobuf.HadoopRpcProtos$HadoopRpcRequestProto$Builder.maybeForceBuilderInitialization()