Removed distinct() in TaskFactory and added a test in AbstractBuildMo…

…jo instead (root cause)

build-caching/src/main/java/com/vertispan/j2cl/build/Dependency.java

@@ -15,6 +15,8 @@
  */
 package com.vertispan.j2cl.build;
 
+import java.util.Objects;
+
 /**
  * A dependency is a reference to another project's contents, scoped to indicate whether these are
  * required to be compiled against, or linked against (and so are required at runtime). The default
@@ -59,4 +61,20 @@ public Scope getScope() {
     public void setScope(Scope scope) {
         this.scope = scope;
     }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+
+        Dependency that = (Dependency) o;
+        return Objects.equals(project, that.project) && Objects.equals(scope, that.scope);
+    }
+
+    @Override
+    public int hashCode() {
+        int result = Objects.hashCode(project);
+        result = 31 * result + Objects.hashCode(scope);
+        return result;
+    }
 }

build-caching/src/main/java/com/vertispan/j2cl/build/task/TaskFactory.java

@@ -67,7 +67,6 @@ protected List<Project> scope(Collection<? extends Dependency> dependencies, Dep
         return dependencies.stream()
                 .filter(d -> ((com.vertispan.j2cl.build.Dependency) d).belongsToScope(scope))
                 .map(Dependency::getProject)
-                .distinct()
                 .collect(Collectors.toUnmodifiableList());
     }
 

j2cl-maven-plugin/src/main/java/com/vertispan/j2cl/mojo/AbstractBuildMojo.java

@@ -345,7 +345,11 @@ private Project buildProjectHelper(MavenProject mavenProject, Artifact artifact,
             Dependency dep = new Dependency();
             dep.setProject(child);
             dep.setScope(translateScope(mavenDependency.getScope()));
-            dependencies.add(dep);
+            // Although this new dependency is generally unique, the replacement mechanism may introduce a duplicate
+            // dependency if several original artifacts are replaced with the same final artifact.
+            if (!dependencies.contains(dep)) { // ensures we don't introduce a duplicate dependency (important for J2CL)
+                dependencies.add(dep);
+            }
         }
         project.setDependencies(dependencies);