Do not parse generated sources as source files, but only as compiled classes

[timtebeek]

As identified on

• Simplify logic surrounding building of Java & Kotlin parsers. #665 (comment)

I think it boils down to the question if getCompileClasspathElements() returns the classes compiled fom generated sources as well, which could depend on a number of different factors depending on how the code generation is configured.

rewrite-maven-plugin/src/main/java/org/openrewrite/maven/MavenMojoProjectParser.java

Lines 317 to 324 in 0b8fc33

	logInfo(mavenProject, "Parsing source files");
	List<Path> dependencies = mavenProject.getCompileClasspathElements().stream()
	.distinct()
	.map(Paths::get)
	.collect(toList());
	JavaTypeCache typeCache = new JavaTypeCache();
	javaParserBuilder.classpath(dependencies).typeCache(typeCache);
	kotlinParserBuilder.classpath(dependencies).typeCache(new JavaTypeCache());

Right now we define generated sources as anything we find in the target/ directory, and parse those as source.

rewrite-maven-plugin/src/main/java/org/openrewrite/maven/MavenMojoProjectParser.java

Lines 302 to 308 in 0b8fc33

	// Some annotation processors output generated sources to the /target directory. These are added for parsing but
	// should be filtered out of the final SourceFile list.
	List<Path> generatedSourcePaths = listJavaSources(mavenProject.getBasedir().toPath().resolve(mavenProject.getBuild().getDirectory()));
	List<Path> mainJavaSources = Stream.concat(
	generatedSourcePaths.stream(),
	listJavaSources(mavenProject.getBasedir().toPath().resolve(mavenProject.getBuild().getSourceDirectory())).stream()
	).collect(toList());

Before we then later filter out those generated sources.

rewrite-maven-plugin/src/main/java/org/openrewrite/maven/MavenMojoProjectParser.java

Lines 341 to 346 in 9a9428f

	//Filter out any generated source files from the returned list, as we do not want to apply the recipe to the
	//generated files.
	Path buildDirectory = baseDir.relativize(Paths.get(mavenProject.getBuild().getDirectory()));
	Stream<SourceFile> sourceFiles = Stream.concat(parsedJava, parsedKotlin)
	.filter(s -> !s.getSourcePath().startsWith(buildDirectory))
	.map(addProvenance(baseDir, mainProjectProvenance, generatedSourcePaths));

It might be interesting to not parse those generated sources as source files but rather only as classpath entries. I'm not entirely sure that would work in all cases, but it could speed up builds for projects that heavily use generated sources.