code: public @NotNull CharAssert isLowerCase() {
      if (Character.isLowerCase(actual)) {
        return this;
      }
      failIfCustomMessageIsSet();
      throw failure(String.format("<%s> should be a lower-case character", actual));
    }
docs: Verifies that the {@code Character} value is an lower-case value.
  
  @return this assertion object.
  @throws AssertionError if the {@code Character} value is not an lower-case value.