Interface method and its implementation

- How to find all implementations of interface method (PsiMethod)?

- How to find interface method by its implementor (PsiMethod)?
This works:

for (HierarchicalMethodSignature sig: method.getHierarchicalMethodSignature().getSuperSignatures()) {
     PsiMethod superMethod = sig.getMethod();
     PsiClass superClass = superMethod.getContainingClass();
     if (superClass != null && superClass.isInterface()) {
          return superMethod;
     }
}

Is there better way?