@Override
  public int hashCode() {
    int result = getDigest().hashCode();
    result = 31 * result + (schema != null ? schema.hashCode() : 0);
    return result;
  }
A copy of this map.
<p>Called to avoid sharing instances from cache.</p>

@return a shallow copy of this map
standalone-metastore/metastore-common/src/main/java/org/apache/hadoop/hive/metastore/properties/PropertyMap.java