Make exception messages match Maven 3 again

The boxing of `MojoException` into a `MojoExecutionException` brought two issues:

1. It added another layer to the stacktrace, making it a bit less readable for users and breaking test expectations for Maven extension authors (this was my main motivation for this change)
2. It lost the `longMessage`, which meant that this message was no longer shown at the end of the build.

This change fixes both problems by passing through the original `MojoException` and treating this new exception type directly in `DefaultExceptionHandler` and `MojoExecutor`

maven-core/src/main/java/org/apache/maven/exception/DefaultExceptionHandler.java

@@ -30,6 +30,7 @@
 import java.util.List;
 import java.util.Set;
 
+import org.apache.maven.api.plugin.MojoException;
 import org.apache.maven.lifecycle.LifecycleExecutionException;
 import org.apache.maven.model.building.ModelProblem;
 import org.apache.maven.model.building.ModelProblemUtils;
@@ -232,16 +233,20 @@ private String getMessage(String message, Throwable exception) {
  Set<Throwable> dejaVu = Collections.newSetFromMap(new IdentityHashMap<>());
  for (Throwable t = exception; t != null && t != t.getCause(); t = t.getCause()) {
  String exceptionMessage = t.getMessage();
+ String longMessage = null;
 
  if (t instanceof AbstractMojoExecutionException) {
- String longMessage = ((AbstractMojoExecutionException) t).getLongMessage();
- if (longMessage != null && !longMessage.isEmpty()) {
- if ((exceptionMessage == null || exceptionMessage.isEmpty())
- || longMessage.contains(exceptionMessage)) {
- exceptionMessage = longMessage;
- } else if (!exceptionMessage.contains(longMessage)) {
- exceptionMessage = join(exceptionMessage, System.lineSeparator() + longMessage);
- }
+ longMessage = ((AbstractMojoExecutionException) t).getLongMessage();
+ } else if (t instanceof MojoException) {
+ longMessage = ((MojoException) t).getLongMessage();
+ }
+
+ if (longMessage != null && !longMessage.isEmpty()) {
+ if ((exceptionMessage == null || exceptionMessage.isEmpty())
+ || longMessage.contains(exceptionMessage)) {
+ exceptionMessage = longMessage;
+ } else if (!exceptionMessage.contains(longMessage)) {
+ exceptionMessage = join(exceptionMessage, System.lineSeparator() + longMessage);
  }
  }
 

maven-core/src/main/java/org/apache/maven/lifecycle/internal/MojoExecutor.java

@@ -37,6 +37,7 @@
 import java.util.concurrent.locks.ReentrantReadWriteLock;
 
 import org.apache.maven.api.SessionData;
+import org.apache.maven.api.plugin.MojoException;
 import org.apache.maven.api.services.MessageBuilderFactory;
 import org.apache.maven.artifact.Artifact;
 import org.apache.maven.artifact.resolver.filter.ArtifactFilter;
@@ -324,7 +325,8 @@ private void doExecute2(MavenSession session, MojoExecution mojoExecution) throw
  } catch (MojoFailureException
  | PluginManagerException
  | PluginConfigurationException
- | MojoExecutionException e) {
+ | MojoExecutionException
+ | MojoException e) {
  throw new LifecycleExecutionException(
  messageBuilderFactory, mojoExecution, session.getCurrentProject(), e);
  }

maven-core/src/main/java/org/apache/maven/plugin/DefaultBuildPluginManager.java

@@ -27,7 +27,7 @@
 import java.util.List;
 
 import org.apache.maven.api.Project;
-import org.apache.maven.api.plugin.MojoException;
+import org.apache.maven.api.services.MavenException;
 import org.apache.maven.execution.MavenSession;
 import org.apache.maven.execution.MojoExecutionEvent;
 import org.apache.maven.execution.MojoExecutionListener;
@@ -143,12 +143,14 @@ public void executeMojo(MavenSession session, MojoExecution mojoExecution)
  mojoExecutionListener.beforeMojoExecution(mojoExecutionEvent);
  mojo.execute();
  mojoExecutionListener.afterMojoExecutionSuccess(mojoExecutionEvent);
- } catch (ClassCastException e) {
+ } catch (ClassCastException | MavenException e) {
  // to be processed in the outer catch block
  throw e;
  } catch (RuntimeException e) {
  throw new PluginExecutionException(mojoExecution, project, e);
  }
+ } catch (MavenException e) {
+ throw e;
  } catch (PluginContainerException e) {
  mojoExecutionListener.afterExecutionFailure(
  new MojoExecutionEvent(session, project, mojoExecution, mojo, e));
@@ -226,12 +228,8 @@ private static class MojoWrapper implements Mojo {
  }
 
  @Override
- public void execute() throws MojoExecutionException, MojoFailureException {
- try {
- mojoV4.execute();
- } catch (MojoException e) {
- throw new MojoExecutionException(e.getMessage(), e);
- }
+ public void execute() {
+ mojoV4.execute();
  }
 
  @Override