public static byte[] serialize(String source, Throwable t) {
    return toProto(source, t).toByteArray();
  }
Converts a RemoteProcedureException to an array of bytes.
@param source the name of the external exception source
@param t      the "local" external exception (local)
@return protobuf serialized version of RemoteProcedureException
hbase-procedure/src/main/java/org/apache/hadoop/hbase/procedure2/RemoteProcedureException.java