import com.google.common.collect.testing.features.CollectionSize;
import org.junit.Ignore;

/**
 * A generic JUnit test which tests {@code isEmpty()} operations on a map. Can't be invoked
 * directly; please see {@link com.google.common.collect.testing.MapTestSuiteBuilder}.
 *
 * @author Kevin Bourrillion
 */
@GwtCompatible

 * parameter, the object containing the method will not be able to register for event delivery from
 * the {@link EventBus}.
 *
 * <p>Unless also annotated with @{@link AllowConcurrentEvents}, event subscriber methods will be
 * invoked serially by each event bus that they are registered with.
 *
 * @author Cliff Biffle
 * @since 10.0
 */
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
@Keep

import com.google.common.annotations.GwtCompatible;
import org.junit.Ignore;

/**
 * A generic JUnit test which tests {@code get()} operations on a list. Can't be invoked directly;
 * please see {@link com.google.common.collect.testing.ListTestSuiteBuilder}.
 *
 * @author Chris Povirk
 */
@GwtCompatible

 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.maven.cling.invoker.mvnsh;

import java.util.ArrayList;
import java.util.List;

import org.jline.console.CommandRegistry;

import static java.util.Objects.requireNonNull;

 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.maven.cling.invoker.mvn;

public final class Environment {
    private Environment() {}

    public static final String TOOLBOX_VERSION = System.getProperty("version.toolbox", "UNSET version.toolbox");

## An app with callbacks { #an-app-with-callbacks }

Let's see all this with an example.

Imagine you develop an app that allows creating invoices.

These invoices will have an `id`, `title` (optional), `customer`, and `total`.

The user of your API (an external developer) will create an invoice in your API with a POST request.

Then your API will (let's imagine):

 *
 * <p><b>{@code default} method warning:</b> This class does <i>not</i> forward calls to {@code
 * default} methods. Instead, it inherits their default implementations. When those implementations
 * invoke methods, they invoke methods on the {@code ForwardingBlockingDeque}.
 *
 * <p>The {@code standard} methods are not guaranteed to be thread-safe, even when all of the
 * methods that they depend on are thread-safe.
 *

import com.google.common.collect.testing.features.CollectionSize;
import org.junit.Ignore;

/**
 * A generic JUnit test which tests remove operations on a set. Can't be invoked directly; please
 * see {@link com.google.common.collect.testing.ListTestSuiteBuilder}.
 *
 * @author George van den Driessche
 */
@GwtCompatible

import com.google.common.collect.testing.features.CollectionSize;
import org.junit.Ignore;

/**
 * A generic JUnit test which tests remove operations on a set. Can't be invoked directly; please
 * see {@link com.google.common.collect.testing.ListTestSuiteBuilder}.
 *
 * @author George van den Driessche
 */
@GwtCompatible

 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.maven.cling.invoker.cisupport;

import java.util.ArrayList;
import java.util.List;
import java.util.Optional;
import java.util.ServiceLoader;
import java.util.stream.Collectors;

import org.apache.maven.api.cli.cisupport.CIInfo;