@Override
    public Optional<String> getRegionServerGroup() {
      Bytes value = values.get(RSGROUP_KEY);
      if (value != null) {
        return Optional.of(Bytes.toString(value.get(), value.getOffset(), value.getLength()));
      } else {
        return Optional.empty();
      }
    }
@param bytes A pb serialized {@link ModifyableTableDescriptor} instance with pb magic prefix
@return An instance of {@link ModifyableTableDescriptor} made from <code>bytes</code>
@see #toByteArray()
hbase-client/src/main/java/org/apache/hadoop/hbase/client/TableDescriptorBuilder.java