Fixes #8: m2eclipse 1.x and 2.x compatibility

com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/scoping/MavenResolverHelper.java

@@ -1,14 +1,15 @@
 package com.google.eclipse.protobuf.ui.scoping;
 
-import java.lang.reflect.InvocationTargetException;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 import org.apache.maven.artifact.Artifact;
+import org.apache.maven.project.MavenProject;
 import org.apache.maven.project.ProjectBuildingRequest;
 import org.eclipse.core.resources.IProject;
 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.m2e.core.MavenPlugin;
+import org.eclipse.m2e.core.embedder.IMaven;
 import org.eclipse.m2e.core.embedder.IMavenExecutionContext;
 import org.eclipse.m2e.core.internal.IMavenConstants;
 import org.eclipse.m2e.core.project.IMavenProjectFacade;
@@ -19,52 +20,21 @@ public final class MavenResolverHelper {
 
 	public static List<DirectoryPath> resolveMavenDependencies(IProject aProject) throws CoreException {
 		if (aProject.isOpen() && aProject.hasNature(IMavenConstants.NATURE_ID)) {
-			final IMavenProjectFacade facade = MavenPlugin.getMavenProjectRegistry().getProject(aProject);
-
-			final IMavenExecutionContext context;
+			final IMavenProjectFacade facade = MavenPlugin.getMavenProjectRegistry().getProject(aProject);	
 
-			try {
-				Class<?> toolboxClass = MavenResolverHelper.class.getClassLoader()
-					.loadClass("org.eclipse.m2e.core.internal.IMavenToolbox");
-
-				// If the class can be loaded, m2e 2.x is installed. We compile against 1.x (because we compile
-				// against Neon, which is the minimum necessary for this plugin) so we must implement the slight
-				// breaking changes in the dependency resolution via reflection.
-				try {
-					context = (IMavenExecutionContext) facade.getClass().getMethod("createExecutionContext", new Class[0])
-							.invoke(facade, new Object[0]);
-				} catch (IllegalAccessException | IllegalArgumentException | InvocationTargetException
-						| NoSuchMethodException | SecurityException e) {
-					throw new RuntimeException(e);
-				}
-				context.execute((ctx, mon) -> {
-					ProjectBuildingRequest configuration = ctx.newProjectBuildingRequest();
-					configuration.setProject(facade.getMavenProject());
-					configuration.setResolveDependencies(true);
-					try {
-						Object toolbox = toolboxClass.getMethod("of", new Class[] { IMavenExecutionContext.class })
-								.invoke(null, new Object[] { ctx });
-						return toolboxClass
-								.getMethod("readMavenProject",
-										new Class[] { java.io.File.class, ProjectBuildingRequest.class })
-								.invoke(toolbox, new Object[] { facade.getPomFile(), configuration });
-					} catch (IllegalAccessException | IllegalArgumentException
-							| InvocationTargetException | NoSuchMethodException | SecurityException exc) {
-						throw new RuntimeException(exc);
-					}
-				}, null);
-
-			} catch(ClassNotFoundException exc) {
-				// Expected in case of m2e 1.x which does not yet have the IMavenToolbox.
-				// We can directly invoke it here.
-				ProjectBuildingRequest configuration = MavenPlugin.getMaven().getExecutionContext().newProjectBuildingRequest();
+			final IMaven maven =  MavenPlugin.getMaven();
+			final IMavenExecutionContext context = maven.createExecutionContext();
+			context.execute((ctx, mon) -> {
+				final ProjectBuildingRequest configuration = ctx.newProjectBuildingRequest();
 			    configuration.setProject(facade.getMavenProject());
 			    configuration.setResolveDependencies(true);
-			    MavenPlugin.getMaven().readMavenProject(facade.getPomFile(), configuration);
-			}
+			    return MavenPlugin.getMaven().readMavenProject(facade.getPomFile(), configuration);
+			}, null);
+
+			final MavenProject mavenProject = facade.getMavenProject(null);
 
 			ArrayList<DirectoryPath> paths = new ArrayList<>();
-			for (Artifact artifact : facade.getMavenProject().getArtifacts()) {
+			for (Artifact artifact : mavenProject.getArtifacts()) {
 				if (artifact.getFile() != null) {
 					paths.add(DirectoryPath.parse(artifact.getFile().getAbsolutePath(), aProject));
 					artifact.getFile();