So, offline mode has several implications, some of which may not be
  altogether obvious:

  * Localhost may be unavailable. Therefore, even locally installed
    server processes which work by conversing over a port may fail.

  * Not all "remote" repositories will fail. Specifically, if the remote
    repo uses the file:// protocol, and it doesn't refer to a shared
    filesystem, it will continue to be available.

                    addViolation(
                            problems,
                            BuilderProblem.Severity.ERROR,
                            "proxies.proxy[" + proxy.getId() + "].port",
                            null,
                            "must be a valid integer but found '" + proxy.getPortString() + "'");
                }
            }
        }
    }

        return context.get(key);
    }

    /**
     * Sets the project's class realm. <strong>Warning:</strong> This is an internal utility method that is only public
     * for technical reasons, it is not part of the public API. In particular, this method can be changed or deleted
     * without prior notice and must not be used by plugins.
     *

         * starting at the root object contained in this value source, apply each part
         * to the object graph below this root, using either 'getXXX()' or 'isXXX()'
         * accessor types to resolve the value for each successive expression part.
         * Finally, return the result of the last expression part's resolution.</p>
         *

import org.eclipse.aether.resolution.ArtifactDescriptorResult;

/**
 * Populates Aether {@link ArtifactDescriptorResult} from Maven project {@link Model}.
 * <p>
 * <strong>Note:</strong> This class is part of work in progress and can be changed or removed without notice.
 * @since 3.2.4
 */
public class ArtifactDescriptorReaderDelegate {

import org.eclipse.aether.repository.LocalRepositoryManager;
import org.eclipse.aether.repository.RemoteRepository;

/**
 * <strong>Warning:</strong> This is an internal utility class that is only public for technical reasons, it is not part
 * of the public API. In particular, this class can be changed or deleted without prior notice.
 *
 */
@Deprecated
public class LegacyLocalRepositoryManager implements LocalRepositoryManager {

     * same class realm is used to load build extensions and load mojos for extensions=true plugins.
     * </p>
     * <strong>Note:</strong> This is part of internal implementation and may be changed or removed without notice
     *
     * @since 3.3.0
     */
    public static final String KEY_EXTENSIONS_REALMS = DefaultMavenPluginManager.class.getName() + "/extensionsRealms";

import org.apache.maven.project.MavenProject;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * <p>
 * Executes an individual mojo
 * </p>
 * <strong>NOTE:</strong> This class is not part of any public api and can be changed or deleted without prior notice.
 *
 * @since 3.0
 */
@Named
@Singleton
public class MojoExecutor {

            boolean projectCompiledDuringThisSession =
                    project.hasLifecyclePhase("compile") && COMPILE_PHASE_TYPES.contains(type);

            // Check if the project is part of the session (not filtered by -pl, -rf, etc). If so, we check
            // if a possible earlier Maven invocation produced some output for that project which we can use.
            boolean projectHasOutputFromPreviousSession =

          </description>
          <type>String</type>
        </field>
        <field>
          <name>post</name>
          <version>3.0.0+</version>
          <description>
            The email address or link that can be used to post to
            the mailing list.  If this is an email address, a
            {@code mailto:} link will automatically be created