code: @VisibleForTesting
  	public boolean onlyKeyExists(String name) {
  		String[] names = handleDeprecation(deprecationContext.get(), name);
  		for(String n : names) {
  			if ( getProps().getProperty(n,DEFAULT_STRING_CHECK)
  					.equals(DEFAULT_STRING_CHECK) ) {
  				return true;
  			}
  		}
  		return false;
  	}
docs: Return existence of the <code>name</code> property, but only for
  names which have no valid value, usually non-existent or commented
  out in XML.
  
  @param name the property name
  @return true if the property <code>name</code> exists without value