The expression return $this->parents returns the type AmaTeam\ElasticSearch\AP...y\DescriptorInterface[] which is incompatible with the return type mandated by AmaTeam\ElasticSearch\AP...Interface::getParents() of AmaTeam\ElasticSearch\AP...erarchy\NodeInterface[].
In the issue above, the returned value is violating the contract defined by the
mentioned interface.
Let's take a look at an example:
interfaceHasName{/** @return string */publicfunctiongetName();}className{public$name;}classUserimplementsHasName{/** @return string|Name */publicfunctiongetName(){returnnewName('foo');// This is a violation of the ``HasName`` interface// which only allows a string value to be returned.}}
In the issue above, the returned value is violating the contract defined by the mentioned interface.
Let's take a look at an example: