### Question:
WorkbenchPreferenceScopeTypes implements PreferenceScopeTypes { protected boolean isEmpty(String str) { return str == null || str.trim().isEmpty(); } protected  WorkbenchPreferenceScopeTypes(); @Inject  WorkbenchPreferenceScopeTypes(final UsernameProvider usernameProvider); @Override boolean typeRequiresKey(final String type); @Override String getDefaultKeyFor(final String type);  }### Answer:
@Test public void isEmptyTest() { assertTrue(scopeTypes.isEmpty(null)); assertTrue(scopeTypes.isEmpty("")); assertTrue(scopeTypes.isEmpty(" ")); assertFalse(scopeTypes.isEmpty("anyString")); }