m2e plugin does not copy resources from src/main/resources, probably regression in 2022-12

[robserm]

I noticed that the newest Eclipse 2022-12 does not copy resources, this is a regression compared to Eclipse 2022-09 .
Steps to reproduce:
-import the attached project as "Existing Maven Project'
resources_problem.zip
-select file examples.stackmachine.RunnableStackMachine and from context menu choose "Run As-> Java Application"

the result is NPE:
Exception in thread "main" java.lang.NullPointerException: Cannot invoke "java.net.URL.toExternalForm()" because "location" is null
at java.desktop/javax.swing.ImageIcon.(ImageIcon.java:234)
at examples.stackmachine.RunnableStackMachine$ImageButton.(RunnableStackMachine.java:372)
at examples.stackmachine.RunnableStackMachine$PushButton.(RunnableStackMachine.java:300)
at examples.stackmachine.RunnableStackMachine.createStackButtonPanel(RunnableStackMachine.java:131)
at examples.stackmachine.RunnableStackMachine.createStackPanel(RunnableStackMachine.java:117)
at examples.stackmachine.RunnableStackMachine.(RunnableStackMachine.java:41)
at examples.stackmachine.RunnableStackMachine.main(RunnableStackMachine.java:392)

The problem is that the images from src/main/resources/examples/stackmachine/img were not copied to target/classes

The problem DOES NOT occur on 2022-09.

If you remove "Excluded" filter from project "Java Build Path" everything works fine, see the image below.

[glhez]

I do have the same issue: the rule includes all, but is excluded directly.

It seems the default value for exclusion is indeed "**" : https://github.com/eclipse-m2e/m2e-core/blame/master/org.eclipse.m2e.jdt/src/org/eclipse/m2e/jdt/internal/AbstractJavaProjectConfigurator.java#L551

Where it should be perhaps be "**/*.java".

Note sure while it fails now since the commit date from 6 years ago - probably the file were included in the runtime classpath of launch configuration ?

[HannesWell]

It seems the default value for exclusion is indeed "**" : https://github.com/eclipse-m2e/m2e-core/blame/master/org.eclipse.m2e.jdt/src/org/eclipse/m2e/jdt/internal/AbstractJavaProjectConfigurator.java#L551

I'm not entirely sure but I assume that the exclusions you are referring only affect the elements are (tried) to be compiled. And since resources are not compiled this makes sense.

The problem is that the images from src/main/resources/examples/stackmachine/img were not copied to target/classes

The problem DOES NOT occur on 2022-09.

Regarding copying resources, we had regressions in the M2E release contributed to 2022-12 SimRel:

• Resources handling is broken when there is a .mvn folder #1150
• [regression] MavenExecutionContext.execute(MavenProject, MojoExecution, IProgressMonitor) loses the MojoExecution configuration #1304

But they have been fixed in

• Fix wrong realm used when executing mojos #1161
• Properly clone mojoExecution #1305

Both available in the latest (just released) M2E release. Therefore can you please try the latest M2E release and check if the issue is already solved. The p2-repo is at:
https://download.eclipse.org/technology/m2e/releases/latest/

[robserm]

Confirmed, Eclipse 2022-12 works fine if m2e is upgraded to the latest version.
The issue can be closed. Thank you very much.

[HannesWell]

Great, thanks for checking it.

[glhez]

Hello @HannesWell

I tried the following version:

And then:

1. removed project from workspace
2. cleaned .project/classpath using git clean -fxd
3. reimported them

But the "**" is still there.

As it seems to work (resource was there after the clean), I'm curious of the change ?

Is this because potential maven plugins may perform copy (or filtering) of resources and the default copy of Eclipse can't work in those case ?

[laeubi]

@glhez I think you are misinterpreting what happening here.

lets say you have a source folder, what will happen:

1. JDT will put anything not excluded on the classpath, but never copies anything!
2. JDT will try to compile any java class and put it on the output folder (what might be different from what maven uses!)

So the exclude ** is used to make this folder visible to the user as a source folder, but disable the default JDT action

under the hood now, maven copies everything from the resource folder to the target/classes folder, and that content is also on the claspath, so now it "works", but the content is/was never used from the resource folder directly!

[glhez]

That's more or less what I understood. Thanks for the reply.

[martinlippert]

Based on some recent comments that we got at the Spring Tools issue tracker, it looks like the issue is still around, but occurs less often: spring-projects/spring-tools#929 (comment)

[laeubi]

@martinlippert if you can provide a test-case that reproduce the issue that would be good, otherwise its a bit hard to tell why it should still occur, especially if it does not happen always.

[glhez]

@laeubi , @martinlippert I remember running in debug Eclipse and stopping in debug near maven-resources-plugin (here: https://maven.apache.org/plugins/maven-resources-plugin/xref/index.html line 293)

My observation were that maven-resources-plugin perform the copy (files are found in explorer when browsing
target/classes) but something after delete the resources

If you use Alt + F5 (or "Maven configure"), the "Clean" checkbox is checked by default : try without it.
I also think that cleaning the whole workspace (as opposed to one single project, to force recompilation and copy of resources)

Observation aside, I don't know what is performing the clean (m2e, maven, Eclipse...).

[martinlippert]

@martinlippert if you can provide a test-case that reproduce the issue that would be good, otherwise its a bit hard to tell why it should still occur, especially if it does not happen always.

Agree, @BoykoAlex is also looking into this to see if we can provide more details here. The description in spring-projects/spring-tools#929 (comment) provides a few steps how to possibly reproduce the issue.

[BoykoAlex]

@laeubi there is a reproducible scenario described here: spring-projects/spring-tools#929 (comment)

I see that resources are not copied into the target folder as well as sometimes .class files are missing as well. If I debug JavaBuilder and MavenBuilder with its build participants (one of them is the mojo execution for the maven resources plugin) it all works fine. However, once breakpoints are skipped the issue occurs. Feels like a timing issue... i.e. downstream project is being built before upstream projects are finished building... perhaps a scheduling rule issue...

[laeubi]

That's quite vague, I think what would be required is a test-case that shows the problem in an isolated way so we can better investigate on it, also it might help to build the failing projects with -T64 to see if it is maybe a dependency issue but I must confess I can't see why a copy resources (what is local to the project) should interfere with other parts of the build here?

[BoykoAlex]

@laeubi There is a much simpler use case here: spring-projects/spring-tools#929 (comment) that reliably reproduces the issue where resources are missing from the target folder... In fact they are created but later removed (by the JavaBuilder#buildAll(...) i think)

Here is the JUnit you could paste into org.eclipse.m2e.core.ui.tests. Sorry for a few Thread.sleep(...). Had to put them in otherwise the test may fail at asserts after the pom file becomes invalid.

It is important to have Auto Build on!

Anyway, I hope this would provide you enough info to investigate matters on your end.

package org.eclipse.m2e.core.ui.tests;

import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;

import java.io.ByteArrayInputStream;
import java.io.File;
import java.nio.file.Files;
import java.nio.file.Path;

import org.apache.commons.io.FileUtils;
import org.eclipse.core.resources.IFile;
import org.eclipse.core.resources.IProject;
import org.eclipse.core.runtime.IPath;
import org.eclipse.jdt.core.IJavaProject;
import org.eclipse.jdt.core.JavaCore;
import org.eclipse.m2e.tests.common.AbstractMavenProjectTestCase;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

public class AppPropsNotCopiedIntoTargetTest extends AbstractMavenProjectTestCase {
	
	private File projectDirectory;

	@Override
	@Before
	public void setUp() throws Exception {
		super.setUp();
	    setAutoBuilding(true);
		projectDirectory = new File(Files.createTempDirectory("m2e-tests").toFile(), "demo");
		projectDirectory.mkdirs();
		copyDir(new File("resources/projects/demo"), projectDirectory);
	}

	@Override
	@After
	public void tearDown() throws Exception {
		FileUtils.deleteDirectory(this.projectDirectory.getParentFile());
		super.tearDown();
	}

	@Test
	public void test() throws Exception {
		IProject project = importProject(new File(projectDirectory, "pom.xml").toString());
		waitForJobsToComplete(monitor);
		Thread.sleep(5000);

		IJavaProject jp = JavaCore.create(project);

		assertTrue(isAutoBuilding());

		IPath rootPath = project.getWorkspace().getRoot().getLocation();
		
		// Project imported for the first time and built - everything is properly in the target folder
		assertTrue(rootPath.append(jp.getOutputLocation()).append("/application.properties").toFile()
				.exists());
		assertTrue(rootPath.append(jp.getOutputLocation())
				.append("/com/example/demo/DemoApplication.class").makeAbsolute().toFile().exists());

		IFile pomXml = project.getFile("pom.xml");
		String content = Files.readString(Path.of(pomXml.getLocationURI()));
		pomXml.setContents(new ByteArrayInputStream("Nothing".getBytes()), true, false, null);

		waitForJobsToComplete(monitor);
		Thread.sleep(5000);
		// Invalid pom file. JavaBuilder built java sources but MavenBuilder wqs unable to do anything hence no resources in the target folder except for compiled classes
		assertFalse(rootPath.append(jp.getOutputLocation()).append("/application.properties").toFile()
				.exists());
		assertTrue(rootPath.append(jp.getOutputLocation())
				.append("/com/example/demo/DemoApplication.class").toFile().exists());

		pomXml.setContents(new ByteArrayInputStream(content.getBytes()), true, false, null);
		waitForJobsToComplete(monitor);
		Thread.sleep(5000);
		// Valid pom file. Compiled classes and resources should reappear in the target folder. However, resources are missing which makes the test fail
		assertTrue(rootPath.append(jp.getOutputLocation())
				.append("/com/example/demo/DemoApplication.class").toFile().exists());
		assertTrue(rootPath.append(jp.getOutputLocation()).append("/application.properties").toFile()
				.exists());		
	}

}