public static Type getExactSuperType(Type subType, Class<?> searchSuperClass) {
    return GenericTypeReflector.getExactSuperType(subType, searchSuperClass);
  }
Finds the most specific supertype of {@code subType} whose erasure is {@code searchSuperClass}, with
the method {@link GenericTypeReflector#getExactSuperType(Type, Class)}.

@param subType          the subType which we search the super type for
@param searchSuperClass the super type to search for
@return the common super type or {@code null} if non was found
spock-core/src/main/java/org/spockframework/util/GenericTypeReflectorUtil.java