private function assertValidAttribute($attribute)
    {
        if ( ! isset($this->documentChangeSet[$attribute])) {
            throw new \InvalidArgumentException(sprintf(
                'Attribute "%s" is not a valid attribute of the document "%s" in PreUpdateEventArgs.',
                $attribute,
                get_class($this->getDocument())
            ));
        }
    }
private function assertValidAttribute($attribute)
    {
        if ( ! isset($this->documentChangeSet[$attribute])) {
            throw new \InvalidArgumentException(sprintf(
                'Attribute "%s" is not a valid attribute of the document "%s" in PreUpdateEventArgs.',
                $attribute,
                get_class($this->getDocument())
            ));
        }
    }
private function assertValidAttribute ( $ attribute ) { if ( ! isset ( $ this -> documentChangeSet [ $ attribute ] ) ) { throw new \ InvalidArgumentException ( sprintf ( 'Attribute "%s" is not a valid attribute of the document "%s" in PreUpdateEventArgs.' , $ attribute , get_class ( $ this -> getDocument ( ) ) ) ) ; } }
Asserts the attribute exists in changeset.

@param string $attribute
@throws \InvalidArgumentException if the attribute has no changeset
Asserts the attribute exists in changeset .