[WIP] Add ExpandWildcardImportsStep with custom classpath

lib/src/main/java/com/diffplug/spotless/java/ExpandWildcardImportsStep.java

@@ -0,0 +1,87 @@
+/*
+ * Copyright 2025-2026 DiffPlug
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.diffplug.spotless.java;
+
+import java.io.File;
+import java.io.Serial;
+import java.io.Serializable;
+import java.lang.reflect.InvocationTargetException;
+import java.util.Collection;
+import java.util.Objects;
+import java.util.Set;
+
+import com.diffplug.spotless.FormatterFunc;
+import com.diffplug.spotless.FormatterStep;
+import com.diffplug.spotless.JarState;
+import com.diffplug.spotless.Provisioner;
+
+public final class ExpandWildcardImportsStep implements Serializable {
+	@Serial
+	private static final long serialVersionUID = 1L;
+
+	private static final String INCOMPATIBLE_ERROR_MESSAGE = "There was a problem interacting with Java-Parser; maybe you set an incompatible version?";
+	private static final String MAVEN_COORDINATES = "com.github.javaparser:javaparser-symbol-solver-core";
+	public static final String DEFAULT_VERSION = "3.27.1";
+
+	private final Collection<File> typeSolverClasspath;
+	private final JarState.Promised jarState;
+
+	private ExpandWildcardImportsStep(Collection<File> typeSolverClasspath, JarState.Promised jarState) {
+		this.typeSolverClasspath = typeSolverClasspath;
+		this.jarState = jarState;
+	}
+
+	public static FormatterStep create(Set<File> typeSolverClasspath, Provisioner provisioner) {
+		Objects.requireNonNull(provisioner, "provisioner cannot be null");
+		return FormatterStep.create("expandwildcardimports",
+				new ExpandWildcardImportsStep(typeSolverClasspath,
+						JarState.promise(() -> JarState.from(MAVEN_COORDINATES + ":" + DEFAULT_VERSION, provisioner))),
+				ExpandWildcardImportsStep::equalityState,
+				State::toFormatter);
+	}
+
+	private State equalityState() {
+		return new State(typeSolverClasspath, jarState.get());
+	}
+
+	private static class State implements Serializable {
+		@Serial
+		private static final long serialVersionUID = 1L;
+
+		private final Collection<File> typeSolverClasspath;
+		private final JarState jarState;
+
+		public State(Collection<File> typeSolverClasspath, JarState jarState) {
+			this.typeSolverClasspath = typeSolverClasspath;
+			this.jarState = jarState;
+		}
+
+		FormatterFunc toFormatter() {
+			try {
+				return (FormatterFunc) jarState
+						.getClassLoader()
+						.loadClass("com.diffplug.spotless.glue.javaparser.ExpandWildcardsFormatterFunc")
+						.getConstructor(Collection.class)
+						.newInstance(typeSolverClasspath);
+			} catch (ClassNotFoundException | NoSuchMethodException | InvocationTargetException
+					| InstantiationException | IllegalAccessException | NoClassDefFoundError cause) {
+				throw new IllegalStateException(INCOMPATIBLE_ERROR_MESSAGE, cause);
+			}
+		}
+
+	}
+
+}

plugin-maven/src/main/java/com/diffplug/spotless/maven/AbstractSpotlessMojo.java

@@ -397,7 +397,7 @@ private FormatterConfig getFormatterConfig() {
 		FileLocator fileLocator = getFileLocator();
 		final Optional<String> optionalRatchetFrom = Optional.ofNullable(this.ratchetFrom)
 				.filter(ratchet -> !RATCHETFROM_NONE.equals(ratchet));
-		return new FormatterConfig(baseDir, encoding, lineEndings, optionalRatchetFrom, provisioner, fileLocator, formatterStepFactories, Optional.ofNullable(setLicenseHeaderYearsFromGitHistory), lintSuppressions);
+		return new FormatterConfig(baseDir, encoding, lineEndings, optionalRatchetFrom, provisioner, fileLocator, formatterStepFactories, Optional.ofNullable(setLicenseHeaderYearsFromGitHistory), lintSuppressions, Optional.ofNullable(project));
 	}
 
 	private FileLocator getFileLocator() {

plugin-maven/src/main/java/com/diffplug/spotless/maven/FormatterConfig.java

@@ -20,6 +20,9 @@
 import java.io.File;
 import java.util.List;
 import java.util.Optional;
+import java.util.Set;
+
+import org.apache.maven.project.MavenProject;
 
 import com.diffplug.spotless.LineEnding;
 import com.diffplug.spotless.LintSuppression;
@@ -35,9 +38,10 @@ public class FormatterConfig {
 	private final List<FormatterStepFactory> globalStepFactories;
 	private final Optional<String> spotlessSetLicenseHeaderYearsFromGitHistory;
 	private final List<LintSuppression> lintSuppressions;
+	private final Optional<MavenProject> mavenProject;
 
 	public FormatterConfig(File baseDir, String encoding, LineEnding lineEndings, Optional<String> ratchetFrom, Provisioner provisioner,
-			FileLocator fileLocator, List<FormatterStepFactory> globalStepFactories, Optional<String> spotlessSetLicenseHeaderYearsFromGitHistory, List<LintSuppression> lintSuppressions) {
+			FileLocator fileLocator, List<FormatterStepFactory> globalStepFactories, Optional<String> spotlessSetLicenseHeaderYearsFromGitHistory, List<LintSuppression> lintSuppressions, Optional<MavenProject> mavenProject) {
 		this.encoding = encoding;
 		this.lineEndings = lineEndings;
 		this.ratchetFrom = ratchetFrom;
@@ -46,6 +50,7 @@ public FormatterConfig(File baseDir, String encoding, LineEnding lineEndings, Op
 		this.globalStepFactories = globalStepFactories;
 		this.spotlessSetLicenseHeaderYearsFromGitHistory = spotlessSetLicenseHeaderYearsFromGitHistory;
 		this.lintSuppressions = lintSuppressions;
+		this.mavenProject = mavenProject;
 	}
 
 	public String getEncoding() {
@@ -79,4 +84,8 @@ public FileLocator getFileLocator() {
 	public List<LintSuppression> getLintSuppressions() {
 		return unmodifiableList(lintSuppressions);
 	}
+
+	public Optional<MavenProject> getMavenProject() {
+		return mavenProject;
+	}
 }

plugin-maven/src/main/java/com/diffplug/spotless/maven/FormatterFactory.java

@@ -184,8 +184,12 @@ Optional<String> ratchetFrom(FormatterConfig config) {
 		}
 	}
 
+	protected Optional<Set<File>> getProjectClasspath(FormatterConfig config) {
+		return Optional.empty();
+	}
+
 	private FormatterStepConfig stepConfig(Charset encoding, FormatterConfig config) {
-		return new FormatterStepConfig(encoding, licenseHeaderDelimiter(), ratchetFrom(config), config.getProvisioner(), config.getFileLocator(), config.getSpotlessSetLicenseHeaderYearsFromGitHistory());
+		return new FormatterStepConfig(encoding, licenseHeaderDelimiter(), ratchetFrom(config), config.getProvisioner(), config.getFileLocator(), config.getSpotlessSetLicenseHeaderYearsFromGitHistory(), getProjectClasspath(config));
 	}
 
 	private static List<FormatterStepFactory> gatherStepFactories(List<FormatterStepFactory> allGlobal, List<FormatterStepFactory> allConfigured) {

plugin-maven/src/main/java/com/diffplug/spotless/maven/FormatterStepConfig.java

@@ -15,8 +15,10 @@
  */
 package com.diffplug.spotless.maven;
 
+import java.io.File;
 import java.nio.charset.Charset;
 import java.util.Optional;
+import java.util.Set;
 
 import com.diffplug.spotless.Provisioner;
 
@@ -28,14 +30,16 @@ public class FormatterStepConfig {
 	private final Provisioner provisioner;
 	private final FileLocator fileLocator;
 	private final Optional<String> spotlessSetLicenseHeaderYearsFromGitHistory;
+	private final Optional<Set<File>> projectClasspath;
 
-	public FormatterStepConfig(Charset encoding, String licenseHeaderDelimiter, Optional<String> ratchetFrom, Provisioner provisioner, FileLocator fileLocator, Optional<String> spotlessSetLicenseHeaderYearsFromGitHistory) {
+	public FormatterStepConfig(Charset encoding, String licenseHeaderDelimiter, Optional<String> ratchetFrom, Provisioner provisioner, FileLocator fileLocator, Optional<String> spotlessSetLicenseHeaderYearsFromGitHistory, Optional<Set<File>> projectClasspath) {
 		this.encoding = encoding;
 		this.licenseHeaderDelimiter = licenseHeaderDelimiter;
 		this.ratchetFrom = ratchetFrom;
 		this.provisioner = provisioner;
 		this.fileLocator = fileLocator;
 		this.spotlessSetLicenseHeaderYearsFromGitHistory = spotlessSetLicenseHeaderYearsFromGitHistory;
+		this.projectClasspath = projectClasspath;
 	}
 
 	public Charset getEncoding() {
@@ -61,4 +65,8 @@ public FileLocator getFileLocator() {
 	public Optional<String> spotlessSetLicenseHeaderYearsFromGitHistory() {
 		return spotlessSetLicenseHeaderYearsFromGitHistory;
 	}
+
+	public Optional<Set<File>> getProjectClasspath() {
+		return projectClasspath;
+	}
 }

plugin-maven/src/main/java/com/diffplug/spotless/maven/java/ExpandWildcardImports.java

@@ -0,0 +1,33 @@
+/*
+ * Copyright 2025 DiffPlug
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.diffplug.spotless.maven.java;
+
+import java.io.File;
+import java.util.Collections;
+import java.util.Set;
+
+import com.diffplug.spotless.FormatterStep;
+import com.diffplug.spotless.java.ExpandWildcardImportsStep;
+import com.diffplug.spotless.maven.FormatterStepConfig;
+import com.diffplug.spotless.maven.FormatterStepFactory;
+
+public class ExpandWildcardImports implements FormatterStepFactory {
+	@Override
+	public FormatterStep newFormatterStep(FormatterStepConfig config) {
+		Set<File> classpath = config.getProjectClasspath().orElse(Collections.emptySet());
+		return ExpandWildcardImportsStep.create(classpath, config.getProvisioner());
+	}
+}

plugin-maven/src/main/java/com/diffplug/spotless/maven/java/Java.java

@@ -20,13 +20,18 @@
 import java.io.File;
 import java.nio.file.Path;
 import java.nio.file.Paths;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.Optional;
 import java.util.Set;
 import java.util.stream.Stream;
 
+import org.apache.maven.artifact.DependencyResolutionRequiredException;
 import org.apache.maven.model.Build;
 import org.apache.maven.project.MavenProject;
 
 import com.diffplug.spotless.generic.LicenseHeaderStep;
+import com.diffplug.spotless.maven.FormatterConfig;
 import com.diffplug.spotless.maven.FormatterFactory;
 import com.diffplug.spotless.maven.generic.LicenseHeader;
 
@@ -80,6 +85,10 @@ public void addForbidWildcardImports(ForbidWildcardImports forbidWildcardImports
 		addStepFactory(forbidWildcardImports);
 	}
 
+	public void addExpandWildcardImports(ExpandWildcardImports expandWildcardImports) {
+		addStepFactory(expandWildcardImports);
+	}
+
 	public void addForbidModuleImports(ForbidModuleImports forbidModuleImports) {
 		addStepFactory(forbidModuleImports);
 	}
@@ -92,6 +101,27 @@ public void addCleanthat(CleanthatJava cleanthat) {
 		addStepFactory(cleanthat);
 	}
 
+	@Override
+	protected Optional<Set<File>> getProjectClasspath(FormatterConfig config) {
+		return config.getMavenProject().map(project -> {
+			try {
+				Set<File> classpath = new HashSet<>();
+				// Add compile classpath
+				for (String element : project.getCompileClasspathElements()) {
+					classpath.add(new File(element));
+				}
+				// Add test classpath
+				for (String element : project.getTestClasspathElements()) {
+					classpath.add(new File(element));
+				}
+				return classpath;
+			} catch (DependencyResolutionRequiredException e) {
+				// If we can't resolve dependencies, return empty set
+				return Collections.<File>emptySet();
+			}
+		});
+	}
+
 	private static String fileMask(Path path) {
 		String dir = path.toString();
 		if (!dir.endsWith(File.separator)) {