public function merge( $old, $new ) {
		if ( empty( $old ) ) {
			if ( empty( $new ) ) {
				return null;
			}
			return $this->condition( $new );
		} else if ( empty( $new ) ) {
			return $this->condition( $old );
		}

		return $this->mergeConditions( $this->condition( $old ), $this->condition( $new ) );
	}
public function merge( $old, $new ) {
		if ( empty( $old ) ) {
			if ( empty( $new ) ) {
				return null;
			}
			return $this->condition( $new );
		} else if ( empty( $new ) ) {
			return $this->condition( $old );
		}

		return $this->mergeConditions( $this->condition( $old ), $this->condition( $new ) );
	}
public function merge ( $ old , $ new ) { if ( empty ( $ old ) ) { if ( empty ( $ new ) ) { return null ; } return $ this -> condition ( $ new ) ; } else if ( empty ( $ new ) ) { return $ this -> condition ( $ old ) ; } return $ this -> mergeConditions ( $ this -> condition ( $ old ) , $ this -> condition ( $ new ) ) ; }
Merge group condition attribute.

@param  string|array|Closure|ConditionInterface|null $old
@param  string|array|Closure|ConditionInterface|null $new
@return ConditionInterface|null
Merge group condition attribute .