They are replaced in Maven 4 with Maven 4 API Core's {{{../api/maven-api-core/apidocs/org/apache/maven/api/Type.html}Dependency Types}},
  with default values defined in {{{../maven-resolver-provider/apidocs/org/apache/maven/repository/internal/type/DefaultTypeProvider.html}DefaultTypeProvider}}.

  For compatibility, legacy Maven 3 artifact handlers are still provided:

     * <p>This map may contain null values if the constructor was invoked with {@code resolve}
     * parameter set to false. This is more efficient when only the module existence needs to
     * be tested, and module descriptors are not needed.</p>
     *
     * @see #getModuleNames()
     */
    private final Map<Path, String> descriptors;

    /**
     * Whether module hierarchy was detected. If false, then package hierarchy is assumed.

Copyright (c) 2000-2011 INRIA, France Telecom
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
  notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright

     * Gets the POM whose build plugins are to be scanned for the version.
     *
     * @return The POM whose build plugins are to be scanned for the version or {@code null} to only search the plugin
     *         repositories.
     */
    Model getPom();

    /**
     * Sets the POM whose build plugins are to be scanned for the version.
     *

                    packages.addAll(descriptor.getExportedPackages());
                }
            }
        } catch (IOException ignored) {
            // exports descriptors are entirely optional
        }

        return new CoreExtensionEntry(loader, artifacts, packages, null, null);
    }

    public static CoreExtensionEntry discoverFrom(

                    if (reactorBuildStatus.isHalted()) {
                        break;
                    }
                } catch (Exception e) {
                    break; // Why are we just ignoring this exception? Are exceptions are being used for flow control
                }
            }
        }
    }

        return result;
    }

    /**
     * Get the map of managed versions, removing the originating artifact if it is also in managed versions
     *
     * @param originatingArtifact artifact we are processing
     * @param managedVersions original managed versions
     */
    private ManagedVersionMap getManagedVersionsMap(
            Artifact originatingArtifact, Map<String, Artifact> managedVersions) {

        }

        /*
         * Grab plugin executions that are bound to the selected lifecycle phases from project. The effective model of
         * the project already contains the plugin executions induced by the project's packaging type. Remember, all
         * phases of interest and only those are in the lifecycle mapping, if a phase has no value in the map, we are
         * not interested in any of the executions bound to it.
         */

     * to process and store tracking information ONLY into local repository, not to any other place. This method
     * filters out currently built artifacts, as events are fired for them as well, but their resolved artifact
     * file would point to checked out source-tree, not the local repository.
     * <p>
     * Visible for testing.
     */

 * {@link Consumer} if it is not marked either {@link Consumer} or {@link Provider}.
 * <p>
 * A package can be marked {@link Consumer}. In this case, all types in the package are considered
 * to be a provider type regardless of whether they are marked {@link Consumer} or {@link Provider}.
 *
 * @see Provider
 * @since 4.0.0
 */
@Experimental
@Documented
@Retention(RetentionPolicy.CLASS)