Incompatible PHP OpenAPI changes in PhpStorm 2020.2

PhpStorm 2020.2 introduced support for PHP union types, which resulted in some PSI-breaking changes.

In earlier versions, type hints in parameters, properties, and return types were parsed inconsistently:

• Return types used a separate PhpReturnType wrapper element, which contained the nullability question mark and the actual type's class reference.

• Parameters and properties used no wrapper element: class references and nullability question mark were plain children of Parameter or CLASS_FIELDS.

As of PhpStorm 2020.2, class references with the question mark are uniformly wrapped into the PhpTypeDeclaration element, which is the parent for PhpReturnType, PhpFieldType, and PhpParameterType.

If your existing code fetches a class reference directly from the parent element, it is now required to get PhpTypeDeclaration first, and then call PhpTypeDeclaration#getClassReferences().

Before 2020.2:

private void handleParameterBefore(Parameter parameter) {
  ClassReference classReference = PsiTreeUtil.getChildOfType(parameter, ClassReference.class);
  handleReference(classReference);
}

After 2020.2:

private void handleParameterAfter(Parameter parameter) {
  PhpTypeDeclaration typeDeclaration = PsiTreeUtil.getChildOfType(parameter, PhpTypeDeclaration.class);
  for (ClassReference classReference : typeDeclaration.getClassReferences()) {
    handleReference(classReference);
  }
}

As of PhpStorm 2020.2, PhpReturnType.getClassReference() is deprecated, since there can be multiple class references. This method also became nullable, since in earlier versions an incomplete ? type was parsed just as a question mark, but now it is parsed as PhpTypeDeclaration with empty getClassReferences().

Before 2020.2:

private void handleReturnTypeBefore(PhpReturnType returnType) {
  ClassReference classReference = returnType.getClassReference();
  handleReference(classReference);
}

After 2020.2:

private void handleReturnTypeAfter(PhpReturnType returnType) {
  for (ClassReference classReference : returnType.getClassReferences()) {
    handleReference(classReference);
  }
}