@Override
  public Map<String, byte[]> getAttributesMap() {
    if (attributes == null) {
      return Collections.emptyMap();
    }
    return Collections.unmodifiableMap(attributes);
  }
empty construction. We need this empty construction to keep binary compatibility.
hbase-client/src/main/java/org/apache/hadoop/hbase/client/OperationWithAttributes.java