code: private void genOptFormalTypeParameters(
        List<? extends TypeParameterElement> typeParameters, StringBuilder sb) {
      if (!typeParameters.isEmpty()) {
        sb.append('<');
        for (TypeParameterElement typeParam : typeParameters) {
          genFormalTypeParameter(typeParam, sb);
        }
        sb.append('>');
      }
    }
docs: FormalTypeParameters:
  < FormalTypeParameter+ >
  
  FormalTypeParameter:
  Identifier ClassBound InterfaceBound*