False positive on one_member_abstracts with implements

[dotdoom]

Describe the issue

An abstract class which adds one member method to an existing interface triggers one_member_abstracts.

To Reproduce

abstract class FooBarable {
  void foo();
  void bar();
}

abstract class Bazable implements FooBarable {  // one_member_abstracts
  void baz();
}

Related but a different issue about one_member_abstracts: #990

[pq]

Thanks for the report @dotdoom!