[POC-Issue#5735]: support legacy automate excludeFromFailureFile

[Pankraz76]

• support legacy projects, auto-generation of excludeFromFailureFile pmd/pmd#5735
• [POC-FIX-PMD] maven-pmd-plugin: reactivate PMD - Best practices maven#2331

mvn pmd:check > pmd.txt

workaround:

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package org.apache.maven.impl;

import java.io.*;
import java.nio.file.*;
import java.util.*;
import java.util.regex.*;

public class ExcludeFromFailureFile {

    private static final Pattern PMD_PATTERN = Pattern.compile(
            "PMD Failure: ([\\w\\.]+):(\\d+) Rule:([\\w]+) Priority:\\d+");

    public static void main(String[] args) throws IOException {
        Path logPath = Paths.get("pmd.txt"); // path to pmd.log
        Path propsPath = Paths.get(".pmd/exclude.properties"); // path to exclude.properties

        // Load existing properties
        Properties excludeProps = new Properties();
        if (Files.exists(propsPath)) {
            try (InputStream in = Files.newInputStream(propsPath)) {
                excludeProps.load(in);
            }
        }

        // Parse PMD log and collect new rules
        Map<String, Set<String>> newEntries = new HashMap<>();

        try (BufferedReader reader = Files.newBufferedReader(logPath)) {
            String line;
            while ((line = reader.readLine()) != null) {
                Matcher matcher = PMD_PATTERN.matcher(line);
                if (matcher.find()) {
                    String className = matcher.group(1);
                    String rule = matcher.group(3);

                    newEntries.computeIfAbsent(className, k -> new HashSet<>()).add(rule);
                }
            }
        }

        // Merge with existing properties
        for (Map.Entry<String, Set<String>> entry : newEntries.entrySet()) {
            String key = entry.getKey();
            Set<String> newRules = entry.getValue();

            String existing = excludeProps.getProperty(key);
            Set<String> merged = new TreeSet<>(newRules); // TreeSet to sort and deduplicate

            if (existing != null && !existing.isEmpty()) {
                merged.addAll(Arrays.asList(existing.split(",")));
            }

            excludeProps.setProperty(key, String.join(",", merged));
        }

        // Ensure output directory exists
        Files.createDirectories(propsPath.getParent());

        // Write back merged properties
        try (OutputStream out = Files.newOutputStream(propsPath)) {
            excludeProps.store(out, "Merged PMD exclusions");
        }

        System.out.println("Exclude file updated successfully.");
    }
}

[Pankraz76]

Suggested change

	.map(violation -> String.format("%s:%s", violation.getViolationClass(), violation.getRule()))
	.map(violation -> String.format("%s=%s", violation.getViolationClass(), violation.getRule()))

collision: (only works for one)

org.apache.maven.building.DefaultProblem=MissingOverride
org.apache.maven.model.merge.MavenModelMerger=ForLoopVariableCount
org.apache.maven.model.merge.MavenModelMerger=OneDeclarationPerLine

merge:

org.apache.maven.building.DefaultProblem=MissingOverride
org.apache.maven.model.merge.MavenModelMerger=ForLoopVariableCount,OneDeclarationPerLine

[Pankraz76]

is this any good @oowekyala @adangel?

A simple log to support manual c&p would give quick fix, without breaking anything as just logging.

Then writing the keys into file could be next step, but not needed anymore. This is unique action, need to be done only once. So automation would be questionable.