Mapped Supperclass composite identifier is ignored in child class

Currently $class->isIdentifierComposite value stays "false" if no new identifiers were added on child class..

patch proposal:
around line 270, file: ClassMetadataFactory.php

add line:
$class->isIdentifierComposite = $parent->isIdentifierComposite;

this way if supperclass had composite identifier and child had none identifiers
the result would be as suspected.