core/src/com/google/inject/internal/MoreTypes.java
private static Class<?> declaringClassOf(TypeVariable typeVariable) {
    GenericDeclaration genericDeclaration = typeVariable.getGenericDeclaration();
    return genericDeclaration instanceof Class ? (Class<?>) genericDeclaration : null;
  }
private static Class<?> declaringClassOf(TypeVariable typeVariable) {
    GenericDeclaration genericDeclaration = typeVariable.getGenericDeclaration();
    return genericDeclaration instanceof Class ? (Class<?>) genericDeclaration : null;
  }
Returns the declaring class of {@code typeVariable}, or {@code null} if it was not declared by
a class.