static Matcher<View> withHint(final String substring) {
        return withHint(is(substring));
    }
A custom matcher that checks the hint property of an {@link EditText}. It
accepts either a {@link String} or a {@link Matcher}.
ui/espresso/CustomMatcherSample/app/src/sharedTest/java/com/example/android/testing/espresso/CustomMatcherSample/HintMatcher.java