import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;
import com.google.common.base.Function;
import com.google.common.collect.ImmutableMap;
import com.google.common.util.concurrent.ExecutionError;
import com.google.common.util.concurrent.UncheckedExecutionException;
import com.google.errorprone.annotations.CanIgnoreReturnValue;

        this.providedArtifacts = exports.getExportedArtifacts();

        this.providedArtifactsV4 = providedArtifacts.stream()
                .filter(ga -> ga.startsWith("org.apache.maven:maven-api-"))
                .collect(Collectors.toSet());
    }

    private ClassRealm newRealm(String id) {
        synchronized (world) {
            String realmId = id;

            Random random = new Random();

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):

* Send the invoice to some customer of the external developer.
* Collect the money.
* Send a notification back to the API user (the external developer).
    * This will be done by sending a POST request (from *your API*) to some *external API* provided by that external developer (this is the "callback").

import static com.google.common.truth.Truth.assertThat;
import static java.nio.charset.StandardCharsets.US_ASCII;

import com.google.common.base.Joiner;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import com.google.common.io.Closer;
import com.google.common.io.Files;
import com.google.common.io.Resources;
import com.google.common.reflect.ClassPath.ClassInfo;

 * limitations under the License.
 */

package com.google.common.collect;

import static com.google.common.base.Preconditions.checkElementIndex;
import static com.google.common.base.Preconditions.checkPositionIndex;
import static com.google.common.collect.CollectPreconditions.checkEntryNotNull;
import static java.util.Objects.requireNonNull;

import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;
import com.google.common.base.internal.Finalizer;
import com.google.common.collect.Sets;
import com.google.common.testing.GcFinalization;
import java.io.Closeable;
import java.io.IOException;
import java.io.UncheckedIOException;
import java.lang.ref.Cleaner;
import java.lang.ref.Cleaner.Cleanable;

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.collect;

import static com.google.common.base.Preconditions.checkNotNull;

import com.google.common.annotations.GwtIncompatible;
import com.google.common.primitives.Primitives;

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.collect;

import static com.google.common.base.Preconditions.checkNotNull;

import com.google.common.annotations.GwtCompatible;
import com.google.errorprone.annotations.CanIgnoreReturnValue;

                        } else {
                            t = SENTINEL;
                        }
                        return new Relocation(global, s, t);
                    })
                    .collect(Collectors.toList());
            LOGGER.info("Parsed {} user relocations", relocationList.size());
            return new Relocations(relocationList);
        }
    }

                new TreeMap<>(new PhaseComparator(lifecycle.getPhases()));

        Map<String, String> aliases = lifecycle.getDelegate().aliases().stream()
                .collect(Collectors.toMap(a -> a.v3Phase(), a -> a.v4Phase()));

        if (aliases.containsKey(lifecyclePhase)) {
            lifecyclePhase = PhaseId.of(aliases.get(lifecyclePhase)).phase();
        }