code: protected function validateElementValues() {
      		// Iterate over all fields
          	foreach ( self::$mandatoryFields as $field ) {
          		// If the field does not exist then exit with exception
          		if ( array_key_exists($field, $this->attributes) ) {
          			$value = (int) $this->attributes[$field];
          			if ( $value < 0 ) {
          				throw new \SVGCreator\SVGException("The " . $field . " value is lesser than 0, in element " . self::TYPE, 1);
          			}
          		}
          	}
      	}
docs: Specific implementation for validation of element values
  
  @throws \SVGCreator\SVGException
  @return void