code: public String getString(String propertyPath, String defaultValue) {
  		Object o = getValue(propertyPath, defaultValue);
  		if (o != null) {
  			return o.toString();
  		} else {
  			// if the defaultValue is null
  			return (String) o;
  		}
  	}
docs: Get the String-value from the property path. If the property path does
  not exist, the default value is returned.
  
  @param propertyPath
  Example: foo.bar.key
  @param defaultValue
  is returned when the propertyPath does not exist
  @return the value for the given propertyPath