code: protected String getParentPropertyName(String propertyName) {
  		if (!PropertyAccessorUtils.isIndexedProperty(propertyName)) {
  			return "";
  		}
  		else {
  			return propertyName.substring(0, propertyName.lastIndexOf(PROPERTY_KEY_PREFIX_CHAR));
  		}
  	}
docs: Return the parent property name of an indexed property or the empty string.
  
  @param propertyName the name of the property.
  @return the empty string or the parent property name if it was indexed.