[MSHARED-1454] Expose ConflictData on DependencyNode

[LogFlames]

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In maven-dependency-plugin there are multiple export formats for the dependency tree, these include Json, DOT, GraphML etc. When creating the normal tree all information is there to format it nicely as e.g. Json. However, when running mvn dependency:tree -Dverbose, all nodes are included (as they are VerboseDependencyNode) but since VerboseDependencyNode is internal in maven-dependency-tree there is no (clean) way to include information of which nodes are included or not (see https://issues.apache.org/jira/browse/MDEP-962).

The only current way to include this information would be to parse the toNodeString() output (where excluded nodes are wrapped in parenthesis).

I propose to expose ConflictData on the DependencyNode and make it null for DefaultDependencyNode to allow for more detailed information in the machine-readable formats.

[LogFlames]

Would this be a feasible change to enable verbose logging output in maven-dependency-plugin? If it is preferable I could create a PR to maven-dependency-plugin that is dependent on this one to have all code-changes in context.

@elharo wdyt?

[elharo]

Needs tests.

At first read, I don't understand what this PR is doing or why

[slawekjaranowski]

I would like to not use this library in dependency plugin .... https://issues.apache.org/jira/browse/MDEP-969

[LogFlames]

I will add tests 👍

This PR would be a prerequisite for https://issues.apache.org/jira/browse/MDEP-962. Currently if running mvn dependency:tree -Dverbose=true it outputs:

[INFO] --- dependency:3.6.1:tree (default-cli) @ attackvector ---
[INFO] org.evil:attackvector:jar:1.2
[INFO] +- junit:junit:jar:4.11:test
[INFO] |  \- org.hamcrest:hamcrest-core:jar:1.3:test
[INFO] +- org.postgresql:postgresql:jar:42.6.0:compile
[INFO] |  \- (org.checkerframework:checker-qual:jar:3.31.0:runtime - omitted for duplicate)
[INFO] +- org.springframework:spring-jdbc:jar:5.3.27:compile
[INFO] |  +- org.springframework:spring-beans:jar:5.3.27:compile
[INFO] |  |  \- (org.springframework:spring-core:jar:5.3.27:compile - omitted for duplicate)
[INFO] |  +- org.springframework:spring-core:jar:5.3.27:compile
[INFO] |  |  \- org.springframework:spring-jcl:jar:5.3.27:compile
[INFO] |  \- org.springframework:spring-tx:jar:5.3.27:compile
[INFO] |     +- (org.springframework:spring-beans:jar:5.3.27:compile - omitted for duplicate)
[INFO] |     \- (org.springframework:spring-core:jar:5.3.27:compile - omitted for duplicate)
[...]

This includes dependencies which were omitted in parenthesis and information such as omitted for duplicate, etc

The corresponding JSON output (mvn dependency:tree -Dverbose=true -DoutputType=json) looks like this:

 --- dependency:3.7.0:tree (default-cli) @ attackvector ---
[INFO] {
[INFO]   "groupId": "org.evil",
[INFO]   "artifactId": "attackvector",
[INFO]   "version": "1.2",
[INFO]   "type": "jar",
[INFO]   "scope": "",
[INFO]   "classifier": "",
[INFO]   "optional": "false",
[INFO]   "children": [
[INFO]     {
[INFO]       "groupId": "junit",
[INFO]       "artifactId": "junit",
[INFO]       "version": "4.11",
[INFO]       "type": "jar",
[INFO]       "scope": "test",
[INFO]       "classifier": "",
[INFO]       "optional": "false",
[INFO]       "children": [
[INFO]         {
[INFO]           "groupId": "org.hamcrest",
[INFO]           "artifactId": "hamcrest-core",
[INFO]           "version": "1.3",
[INFO]           "type": "jar",
[INFO]           "scope": "test",
[INFO]           "classifier": "",
[INFO]           "optional": "false"
[INFO]         }
[INFO]         ]
[INFO]     },
[INFO]     {
[INFO]       "groupId": "org.postgresql",
[INFO]       "artifactId": "postgresql",
[INFO]       "version": "42.6.0",
[INFO]       "type": "jar",
[INFO]       "scope": "compile",
[INFO]       "classifier": "",
[INFO]       "optional": "false",
[INFO]       "children": [
[INFO]         {
[INFO]           "groupId": "org.checkerframework",
[INFO]           "artifactId": "checker-qual",
[INFO]           "version": "3.31.0",
[INFO]           "type": "jar",
[INFO]           "scope": "runtime",
[INFO]           "classifier": "",
[INFO]           "optional": "false"
[INFO]         }
[INFO]         ]
[INFO]     },
[INFO]     {
[INFO]       "groupId": "org.springframework",
[INFO]       "artifactId": "spring-jdbc",
[INFO]       "version": "5.3.27",
[INFO]       "type": "jar",
[INFO]       "scope": "compile",
[INFO]       "classifier": "",
[INFO]       "optional": "false",
[INFO]       "children": [
[INFO]         {
[INFO]           "groupId": "org.springframework",
[INFO]           "artifactId": "spring-beans",
[INFO]           "version": "5.3.27",
[INFO]           "type": "jar",
[INFO]           "scope": "compile",
[INFO]           "classifier": "",
[INFO]           "optional": "false",
[INFO]           "children": [
[INFO]             {
[INFO]               "groupId": "org.springframework",
[INFO]               "artifactId": "spring-core",
[INFO]               "version": "5.3.27",
[INFO]               "type": "jar",
[INFO]               "scope": "compile",
[INFO]               "classifier": "",
[INFO]               "optional": "false"
[INFO]             }
[INFO]             ]
[INFO]         },
[INFO]         {
[INFO]           "groupId": "org.springframework",
[INFO]           "artifactId": "spring-core",
[INFO]           "version": "5.3.27",
[INFO]           "type": "jar",
[INFO]           "scope": "compile",
[INFO]           "classifier": "",
[INFO]           "optional": "false",
[INFO]           "children": [
[INFO]             {
[INFO]               "groupId": "org.springframework",
[INFO]               "artifactId": "spring-jcl",
[INFO]               "version": "5.3.27",
[INFO]               "type": "jar",
[INFO]               "scope": "compile",
[INFO]               "classifier": "",
[INFO]               "optional": "false"
[INFO]             }
[INFO]             ]
[INFO]         },
[INFO]         {
[INFO]           "groupId": "org.springframework",
[INFO]           "artifactId": "spring-tx",
[INFO]           "version": "5.3.27",
[INFO]           "type": "jar",
[INFO]           "scope": "compile",
[INFO]           "classifier": "",
[INFO]           "optional": "false",
[INFO]           "children": [
[INFO]             {
[INFO]               "groupId": "org.springframework",
[INFO]               "artifactId": "spring-beans",
[INFO]               "version": "5.3.27",
[INFO]               "type": "jar",
[INFO]               "scope": "compile",
[INFO]               "classifier": "",
[INFO]               "optional": "false"
[INFO]             },
[INFO]             {
[INFO]               "groupId": "org.springframework",
[INFO]               "artifactId": "spring-core",
[INFO]               "version": "5.3.27",
[INFO]               "type": "jar",
[INFO]               "scope": "compile",
[INFO]               "classifier": "",
[INFO]               "optional": "false"
[INFO]             }
[INFO]             ]
[INFO]         }
[INFO]         ]
[INFO]     },
[...]

The argument -Dverbose=true causes maven-dependency-tree it to return VerboseDependencyNodes instead of DefaultDependencyNodes, but important information such as which are omitted, is missing. This is however currently not exposed from the VerboseDependencyNode as these are internal, other than the function toNodeString, where the formatting with parethesis and omitted reason are included.

My goal with this change would be to construct more useful JSON programmatically, where more key-value pairs could be added: "included": true/false, "omitted_reason": ..., without having to parse the toNodeString for example. It would allow the JSON to be constructed with (https://github.com/apache/maven-dependency-plugin/blob/ae19d893bb61a4b8414877721ca25b580c454dad/src/main/java/org/apache/maven/plugins/dependency/tree/JsonDependencyNodeVisitor.java#L123)

    /**
     * Appends the artifact values to the string builder.
     *
     * @param sb  the string builder to append to
     * @param indent  the current indent level
     * @param artifact  the artifact to write
     * @param hasChildren  true if the artifact has children
     */
-    private void appendNodeValues(StringBuilder sb, int indent, Artifact artifact, boolean hasChildren) {
+    private void appendNodeValues(StringBuilder sb, int indent, Artifact artifact, DependencyNode node, boolean hasChildren) {
         appendKeyValue(sb, indent, "groupId", artifact.getGroupId());
         appendKeyValue(sb, indent, "artifactId", artifact.getArtifactId());
         appendKeyValue(sb, indent, "version", artifact.getVersion());
         appendKeyValue(sb, indent, "type", artifact.getType());
         appendKeyValue(sb, indent, "scope", artifact.getScope());
         appendKeyValue(sb, indent, "classifier", artifact.getClassifier());
+        if (node.getGetConflictData() != null) {
+            ConflictData conflictData = node.getGetConflictData();
+            appendKeyValue(sb, indent, "included", conflictData.getWinnerVersion() == null);
+            if (conflictData.getOriginalVersion() != null) {
+                appendKeyValue(sb, indent, "version_updated_from", conflictData.getOriginalVersion());
+            }
+            if (conflictData.getIgnoredScope() != null) {
+                appendKeyValue(sb, indent, "scope_not_updated_to", conflictData.getIgnoredScope());
+            }
+        }
[...]

Using the resolver API directly would be a nice way to solve this as well, as ConflictData is a subset of the Aether's DependencyNode.getData(), which seems to be what the resolver API works with.

[LogFlames]

Happy new year!

Have you had time to look at the comments above? Is it still unclear?