code: public static Matcher<ClassTree> isDirectImplementationOf(String clazz) {
      Matcher<Tree> isProvidedType = isSameType(clazz);
      return new IsDirectImplementationOf(isProvidedType);
    }
docs: Matches any node that is directly an implementation, but not extension, of the given Class.
  
  <p>E.x. {@code class C implements I} will match, but {@code class C extends A} will not.
  
  <p>Additionally, this will only match <i>direct</i> implementations of interfaces. E.g. the
  following will not match:
  
  <p>{@code interface I1 {} interface I2 extends I1 {} class C implements I2 {} ...
  isDirectImplementationOf(I1).match(\/*class tree for C*\/); // will not match }