Bug: Reproducer and fix for #1583

maven-resolver-demos/maven-resolver-demo-snippets/src/main/java/org/apache/maven/resolver/examples/GetDependencyHierarchyWithConflictsStrategies.java

@@ -54,16 +54,36 @@ public static void main(String[] args) throws Exception {
         System.out.println("------------------------------------------------------------");
         System.out.println(GetDependencyHierarchyWithConflictsStrategies.class.getSimpleName());
 
-        runItWithStrategy(args, ConfigurableVersionSelector.NEAREST_SELECTION_STRATEGY);
-        runItWithStrategy(args, ConfigurableVersionSelector.HIGHEST_SELECTION_STRATEGY);
+        CollectRequest collectRequest;
+
+        // okttp cleanly shows difference between nearest/closest
+        collectRequest = new CollectRequest();
+        collectRequest.setRootArtifact(new DefaultArtifact("demo:demo:1.0"));
+        collectRequest.setDependencies(
+                List.of(new Dependency(new DefaultArtifact("com.squareup.okhttp3:okhttp:jar:4.12.0"), "compile")));
+        runItWithStrategy(args, ConfigurableVersionSelector.NEAREST_SELECTION_STRATEGY, collectRequest);
+        runItWithStrategy(args, ConfigurableVersionSelector.HIGHEST_SELECTION_STRATEGY, collectRequest);
+
+        // MENFORCER-408 inspired
+        collectRequest = new CollectRequest();
+        collectRequest.setRootArtifact(new DefaultArtifact("demo:demo:1.0"));
+        collectRequest.setDependencies(List.of(
+                new Dependency(new DefaultArtifact("org.seleniumhq.selenium:selenium-java:jar:3.0.1"), "test")));
+        collectRequest.setManagedDependencies(List.of(
+                new Dependency(new DefaultArtifact("org.seleniumhq.selenium:selenium-java:jar:3.0.1"), "test"),
+                new Dependency(new DefaultArtifact("org.seleniumhq.selenium:selenium-remote-driver:jar:3.0.1"), "test"),
+                new Dependency(new DefaultArtifact("com.codeborne:phantomjsdriver:jar:1.3.0"), "test")));
+        runItWithStrategy(args, ConfigurableVersionSelector.NEAREST_SELECTION_STRATEGY, collectRequest);
+        runItWithStrategy(args, ConfigurableVersionSelector.HIGHEST_SELECTION_STRATEGY, collectRequest);
     }
 
-    private static void runItWithStrategy(String[] args, String selectionStrategy) throws Exception {
+    private static void runItWithStrategy(String[] args, String selectionStrategy, CollectRequest collectRequest)
+            throws Exception {
         System.out.println();
         System.out.println(selectionStrategy);
         try (RepositorySystem system = Booter.newRepositorySystem(Booter.selectFactory(args))) {
             SessionBuilder sessionBuilder = Booter.newRepositorySystemSession(system);
-            sessionBuilder.setConfigProperty(ConflictResolver.CONFIG_PROP_VERBOSE, ConflictResolver.Verbosity.FULL);
+            sessionBuilder.setConfigProperty(ConflictResolver.CONFIG_PROP_VERBOSE, ConflictResolver.Verbosity.STANDARD);
             sessionBuilder.setConfigProperty(DependencyManagerUtils.CONFIG_PROP_VERBOSE, true);
             sessionBuilder.setConfigProperty(
                     ConfigurableVersionSelector.CONFIG_PROP_SELECTION_STRATEGY, selectionStrategy);
@@ -81,10 +101,6 @@ private static void runItWithStrategy(String[] args, String selectionStrategy) t
                     .setTransferListener(null)
                     .build()) {
 
-                CollectRequest collectRequest = new CollectRequest();
-                collectRequest.setRootArtifact(new DefaultArtifact("demo:demo:1.0"));
-                collectRequest.setDependencies(List.of(
-                        new Dependency(new DefaultArtifact("com.squareup.okhttp3:okhttp:jar:4.12.0"), "compile")));
                 collectRequest.setRepositories(Booter.newRepositories(system, session));
 
                 CollectResult result = system.collectDependencies(session, collectRequest);

maven-resolver-util/src/main/java/org/eclipse/aether/util/graph/transformer/ClassicConflictResolver.java

@@ -806,16 +806,6 @@ private static final class ConflictItem extends ConflictResolver.ConflictItem {
         // bit field of OPTIONAL_FALSE and OPTIONAL_TRUE
         int optionalities;
 
-        /**
-         * Bit flag indicating whether one or more paths consider the dependency non-optional.
-         */
-        public static final int OPTIONAL_FALSE = 0x01;
-
-        /**
-         * Bit flag indicating whether one or more paths consider the dependency optional.
-         */
-        public static final int OPTIONAL_TRUE = 0x02;
-
         private ConflictItem(DependencyNode parent, DependencyNode node, String scope, boolean optional) {
             if (parent != null) {
                 this.parent = parent.getChildren();

maven-resolver-util/src/main/java/org/eclipse/aether/util/graph/transformer/ConflictResolver.java

@@ -151,26 +151,31 @@ public class ConflictResolver implements DependencyGraphTransformer {
      */
     public enum Verbosity {
         /**
-         * Verbosity level to be used in all "common" resolving use cases (ie. dependencies to build class path). The
+         * Verbosity level to be used in all "common" resolving use cases (ie dependencies to build class path). The
          * {@link ConflictResolver} in this mode will trim down the graph to the barest minimum: will not leave
          * any conflicting node in place, hence no conflicts will be present in transformed graph either.
          */
         NONE,
 
         /**
-         * Verbosity level to be used in "analyze" resolving use cases (ie. dependency convergence calculations). The
-         * {@link ConflictResolver} in this mode will remove any redundant collected nodes, in turn it will leave one
-         * with recorded conflicting information. This mode corresponds to "classic verbose" mode when
+         * Verbosity level to be used in "analyze" resolving use cases (ie dependency convergence calculations). The
+         * {@link ConflictResolver} in this mode will remove any redundant collected nodes and cycles, in turn it will
+         * leave one with recorded conflicting information. This mode corresponds to "classic verbose" mode when
          * {@link #CONFIG_PROP_VERBOSE} was set to {@code true}. Obviously, the resulting dependency tree is not
          * suitable for artifact resolution unless a filter is employed to exclude the duplicate dependencies.
          */
         STANDARD,
 
         /**
-         * Verbosity level to be used in "analyze" resolving use cases (ie. dependency convergence calculations). The
-         * {@link ConflictResolver} in this mode will not remove any collected node, in turn it will record on all
-         * eliminated nodes the conflicting information. Obviously, the resulting dependency tree is not suitable
-         * for artifact resolution unless a filter is employed to exclude the duplicate dependencies.
+         * Verbosity level to be used in "analyze" resolving use cases (ie dependency convergence calculations). The
+         * {@link ConflictResolver} in this mode will not remove any collected node nor cycle, in turn it will record
+         * on all eliminated nodes the conflicting information. Obviously, the resulting dependency tree is not suitable
+         * for artifact resolution unless a filter is employed to exclude the duplicate dependencies and possible cycles.
+         * Because of left in cycles, user of this verbosity level should ensure that graph post-processing does not
+         * contain elements that would explode on them. In other words, session should be modified with proper
+         * graph transformers.
+         *
+         * @see RepositorySystemSession#getDependencyGraphTransformer()
          */
         FULL
     }