code: public static Properties getSubProperties (
          Properties source, String prefix, String defaultsPrefix)
      {
          // first load up the defaults
          Properties defs = new Properties();
          extractSubProperties(source, defs, defaultsPrefix);
  
          // now load up the desired properties
          Properties dest = new Properties(defs);
          extractSubProperties(source, dest, prefix);
  
          return dest;
      }
docs: Like {@link #getSubProperties(Properties,String)} with the additional functionality of
  loading up defaults for the sub-properties which are identified by the
  <code>defaultsPrefix</code> string.