testSupportedQueryCommand() {
    const editableField = new FieldConstructor('testField');
    const plugin = new TestPlugin();

    const mockPlugin1 = new LooseMock(plugin);
    mockPlugin1.getTrogClassId().$returns('mockPlugin1');
    mockPlugin1.registerFieldObject(editableField);
    mockPlugin1.isEnabled(editableField).$anyTimes().$returns(true);
    mockPlugin1.isSupportedCommand('+indent').$returns(true);
    mockPlugin1.queryCommandValue('+indent').$returns(true);
    mockPlugin1.activeOnUneditableFields().$returns(true);
    mockPlugin1.$replay();

    const mockPlugin2 = new LooseMock(plugin);
    mockPlugin2.getTrogClassId().$returns('mockPlugin2');
    mockPlugin2.registerFieldObject(editableField);
    mockPlugin2.isEnabled(editableField).$anyTimes().$returns(true);
    mockPlugin2.$replay();

    editableField.registerPlugin(mockPlugin1);
    editableField.registerPlugin(mockPlugin2);

    editableField.queryCommandValue('+indent');

    mockPlugin1.$verify();
    mockPlugin2.$verify();
  }
Tests that if a plugin supports a command that its queryCommandValue
gets called and no further plugins can handle the queryCommandValue.
@suppress {missingProperties} suppression added to enable type checking