public static Properties createOverlayedProperties(Properties tblProps, Properties partProps) {
    Properties props = new Properties();
    props.putAll(tblProps);
    if (partProps != null) {
      props.putAll(partProps);
    }
    return props;
  }
Returns the union of table and partition properties,
with partition properties taking precedence.
@param tblProps
@param partProps
@return the overlayed properties
serde/src/java/org/apache/hadoop/hive/serde2/SerDeUtils.java