code: private Key<?> getKey(Type type, Annotation bindingAnnotation) throws ProvisionException {
      if (bindingAnnotation == null) {
        return Key.get(type);
      } else {
        return Key.get(type, bindingAnnotation);
      }
    }
docs: Gets the Guice binding key for a given Java type with optional
  annotations.
  
  @param type Java type to convert in to a key
  @param bindingAnnotation binding annotation for this key
  @return Guice Key instance for this type/annotations
  @throws ProvisionException in case of any failure