@Test
public void isTypeVariable_notGeneric() {

  assertThat(Types.isTypeVariable(TypeToken.of(Integer.class))).isFalse();
  assertThat(Types.isTypeVariable(TypeToken.of(String.class))).isFalse();
  assertThat(Types.isTypeVariable(TypeToken.of(Object.class))).isFalse();
  assertThat(Types.isTypeVariable(TypeToken.of(String[].class))).isFalse();
  assertThat(Types.isTypeVariable(TypeToken.of(Collection.class))).isFalse();
}