[MNG-8515] Use specialized methods

* UnaryOperator<String> instead of Function<String, String>
* BinaryOperator<String> instead of BiFunction<String, String, String>

Author: gnodet

api/maven-api-cli/src/main/java/org/apache/maven/api/cli/Options.java

@@ -21,7 +21,7 @@
 import java.util.Map;
 import java.util.Optional;
 import java.util.function.Consumer;
-import java.util.function.Function;
+import java.util.function.UnaryOperator;
 
 import org.apache.maven.api.annotations.Experimental;
 import org.apache.maven.api.annotations.Nonnull;
@@ -205,7 +205,7 @@ public interface Options {
      * @return a new {@link Options} instance with interpolated values
      */
     @Nonnull
-    Options interpolate(@Nonnull Function<String, String> callback);
+    Options interpolate(@Nonnull UnaryOperator<String> callback);
 
     /**
      * Emits warning messages if deprecated options are used.

api/maven-api-cli/src/main/java/org/apache/maven/api/cli/mvn/MavenOptions.java

@@ -20,7 +20,7 @@
 
 import java.util.List;
 import java.util.Optional;
-import java.util.function.Function;
+import java.util.function.UnaryOperator;
 
 import org.apache.maven.api.annotations.Experimental;
 import org.apache.maven.api.annotations.Nonnull;
@@ -222,5 +222,5 @@ public interface MavenOptions extends Options {
      * @return a new MavenOptions instance with interpolated values
      */
     @Nonnull
-    MavenOptions interpolate(@Nonnull Function<String, String> callback);
+    MavenOptions interpolate(@Nonnull UnaryOperator<String> callback);
 }

api/maven-api-cli/src/main/java/org/apache/maven/api/cli/mvnenc/EncryptOptions.java

@@ -20,7 +20,7 @@
 
 import java.util.List;
 import java.util.Optional;
-import java.util.function.Function;
+import java.util.function.UnaryOperator;
 
 import org.apache.maven.api.annotations.Experimental;
 import org.apache.maven.api.annotations.Nonnull;
@@ -64,5 +64,5 @@ public interface EncryptOptions extends Options {
      * @return a new EncryptOptions instance with interpolated values
      */
     @Nonnull
-    EncryptOptions interpolate(Function<String, String> callback);
+    EncryptOptions interpolate(UnaryOperator<String> callback);
 }

api/maven-api-cli/src/main/java/org/apache/maven/api/cli/mvnsh/ShellOptions.java

@@ -18,7 +18,7 @@
  */
 package org.apache.maven.api.cli.mvnsh;
 
-import java.util.function.Function;
+import java.util.function.UnaryOperator;
 
 import org.apache.maven.api.annotations.Experimental;
 import org.apache.maven.api.annotations.Nonnull;
@@ -39,5 +39,5 @@ public interface ShellOptions extends Options {
      * @return a new EncryptOptions instance with interpolated values
      */
     @Nonnull
-    ShellOptions interpolate(Function<String, String> callback);
+    ShellOptions interpolate(UnaryOperator<String> callback);
 }

api/maven-api-core/src/main/java/org/apache/maven/api/services/Interpolator.java

@@ -23,8 +23,9 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
-import java.util.function.BiFunction;
+import java.util.function.BinaryOperator;
 import java.util.function.Function;
+import java.util.function.UnaryOperator;
 
 import org.apache.maven.api.Service;
 import org.apache.maven.api.annotations.Experimental;
@@ -47,7 +48,7 @@ public interface Interpolator extends Service {
      * @param properties The map containing key-value pairs to be interpolated.
      * @param callback The function to resolve variable values not found in the map.
      */
-    default void interpolate(@Nonnull Map<String, String> properties, @Nullable Function<String, String> callback) {
+    default void interpolate(@Nonnull Map<String, String> properties, @Nullable UnaryOperator<String> callback) {
         interpolate(properties, callback, null, true);
     }
 
@@ -59,7 +60,7 @@ default void interpolate(@Nonnull Map<String, String> properties, @Nullable Func
      * @param defaultsToEmpty If true, unresolved placeholders are replaced with empty strings. If false, they are left unchanged.
      */
     default void interpolate(
-            @Nonnull Map<String, String> map, @Nullable Function<String, String> callback, boolean defaultsToEmpty) {
+            @Nonnull Map<String, String> map, @Nullable UnaryOperator<String> callback, boolean defaultsToEmpty) {
         interpolate(map, callback, null, defaultsToEmpty);
     }
 
@@ -72,8 +73,8 @@ default void interpolate(
      */
     void interpolate(
             @Nonnull Map<String, String> map,
-            @Nullable Function<String, String> callback,
-            @Nullable BiFunction<String, String, String> postprocessor,
+            @Nullable UnaryOperator<String> callback,
+            @Nullable BinaryOperator<String> postprocessor,
             boolean defaultsToEmpty);
 
     /**
@@ -85,7 +86,7 @@ void interpolate(
      * @return The interpolated string, or null if the input was null.
      */
     @Nullable
-    default String interpolate(@Nullable String val, @Nullable Function<String, String> callback) {
+    default String interpolate(@Nullable String val, @Nullable UnaryOperator<String> callback) {
         return interpolate(val, callback, false);
     }
 
@@ -99,7 +100,7 @@ default String interpolate(@Nullable String val, @Nullable Function<String, Stri
      */
     @Nullable
     default String interpolate(
-            @Nullable String val, @Nullable Function<String, String> callback, boolean defaultsToEmpty) {
+            @Nullable String val, @Nullable UnaryOperator<String> callback, boolean defaultsToEmpty) {
         return interpolate(val, callback, null, defaultsToEmpty);
     }
 
@@ -114,8 +115,8 @@ default String interpolate(
     @Nullable
     String interpolate(
             @Nullable String val,
-            @Nullable Function<String, String> callback,
-            @Nullable BiFunction<String, String, String> postprocessor,
+            @Nullable UnaryOperator<String> callback,
+            @Nullable BinaryOperator<String> postprocessor,
             boolean defaultsToEmpty);
 
     /**
@@ -127,9 +128,9 @@ String interpolate(
      *
      * @throws NullPointerException if the input collection is null or contains null elements.
      */
-    static Function<String, String> chain(Collection<? extends Function<String, String>> functions) {
+    static UnaryOperator<String> chain(Collection<? extends UnaryOperator<String>> functions) {
         return s -> {
-            for (Function<String, String> function : functions) {
+            for (UnaryOperator<String> function : functions) {
                 String v = function.apply(s);
                 if (v != null) {
                     return v;
@@ -140,7 +141,7 @@ static Function<String, String> chain(Collection<? extends Function<String, Stri
     }
 
     @SafeVarargs
-    static Function<String, String> chain(Function<String, String>... functions) {
+    static UnaryOperator<String> chain(UnaryOperator<String>... functions) {
         return chain(List.of(functions));
     }
 
@@ -150,14 +151,14 @@ static Function<String, String> chain(Function<String, String>... functions) {
      * improving performance for repeated calls with the same input.
      *
      * @param callback The original function to be memoized. It takes a String as input and returns a String.
-     * @return A new {@code Function<String, String>} that caches the results of the original function.
+     * @return A new {@code UnaryOperator<String>} that caches the results of the original function.
      *         If the original function returns null for a given input, null will be cached and returned for subsequent calls with the same input.
      *
      * @see Function
      * @see Optional
      * @see HashMap#computeIfAbsent(Object, Function)
      */
-    static Function<String, String> memoize(Function<String, String> callback) {
+    static UnaryOperator<String> memoize(UnaryOperator<String> callback) {
         Map<String, Optional<String>> cache = new HashMap<>();
         return s -> cache.computeIfAbsent(s, v -> Optional.ofNullable(callback.apply(v)))
                 .orElse(null);

api/maven-api-core/src/main/java/org/apache/maven/api/services/SettingsBuilderRequest.java

@@ -21,7 +21,7 @@
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.Optional;
-import java.util.function.Function;
+import java.util.function.UnaryOperator;
 
 import org.apache.maven.api.ProtoSession;
 import org.apache.maven.api.annotations.Experimental;
@@ -72,7 +72,7 @@ public interface SettingsBuilderRequest {
      * @return the interpolation source for interpolation
      */
     @Nonnull
-    Optional<Function<String, String>> getInterpolationSource();
+    Optional<UnaryOperator<String>> getInterpolationSource();
 
     @Nonnull
     static SettingsBuilderRequest build(
@@ -136,7 +136,7 @@ class SettingsBuilderRequestBuilder {
         Source installationSettingsSource;
         Source projectSettingsSource;
         Source userSettingsSource;
-        Function<String, String> interpolationSource;
+        UnaryOperator<String> interpolationSource;
 
         public SettingsBuilderRequestBuilder session(ProtoSession session) {
             this.session = session;
@@ -158,7 +158,7 @@ public SettingsBuilderRequestBuilder userSettingsSource(Source userSettingsSourc
             return this;
         }
 
-        public SettingsBuilderRequestBuilder interpolationSource(Function<String, String> interpolationSource) {
+        public SettingsBuilderRequestBuilder interpolationSource(UnaryOperator<String> interpolationSource) {
             this.interpolationSource = interpolationSource;
             return this;
         }
@@ -177,15 +177,15 @@ private static class DefaultSettingsBuilderRequest extends BaseRequest<ProtoSess
             private final Source installationSettingsSource;
             private final Source projectSettingsSource;
             private final Source userSettingsSource;
-            private final Function<String, String> interpolationSource;
+            private final UnaryOperator<String> interpolationSource;
 
             @SuppressWarnings("checkstyle:ParameterNumber")
             DefaultSettingsBuilderRequest(
                     @Nonnull ProtoSession session,
                     @Nullable Source installationSettingsSource,
                     @Nullable Source projectSettingsSource,
                     @Nullable Source userSettingsSource,
-                    @Nullable Function<String, String> interpolationSource) {
+                    @Nullable UnaryOperator<String> interpolationSource) {
                 super(session);
                 this.installationSettingsSource = installationSettingsSource;
                 this.projectSettingsSource = projectSettingsSource;
@@ -213,7 +213,7 @@ public Optional<Source> getUserSettingsSource() {
 
             @Nonnull
             @Override
-            public Optional<Function<String, String>> getInterpolationSource() {
+            public Optional<UnaryOperator<String>> getInterpolationSource() {
                 return Optional.ofNullable(interpolationSource);
             }
         }

compat/maven-embedder/src/main/java/org/apache/maven/cli/ExtensionConfigurationModule.java

@@ -18,7 +18,7 @@
  */
 package org.apache.maven.cli;
 
-import java.util.function.Function;
+import java.util.function.UnaryOperator;
 
 import com.google.inject.Binder;
 import com.google.inject.Module;
@@ -36,10 +36,10 @@
 public class ExtensionConfigurationModule implements Module {
 
     private final CoreExtensionEntry extension;
-    private final Function<String, String> callback;
+    private final UnaryOperator<String> callback;
     private final DefaultInterpolator interpolator = new DefaultInterpolator();
 
-    public ExtensionConfigurationModule(CoreExtensionEntry extension, Function<String, String> callback) {
+    public ExtensionConfigurationModule(CoreExtensionEntry extension, UnaryOperator<String> callback) {
         this.extension = extension;
         this.callback = callback;
     }
@@ -51,8 +51,8 @@ public void configure(Binder binder) {
             if (configuration == null) {
                 configuration = new XmlNodeImpl("configuration");
             }
-            Function<String, String> cb = Interpolator.memoize(callback);
-            Function<String, String> it = s -> interpolator.interpolate(s, cb);
+            UnaryOperator<String> cb = Interpolator.memoize(callback);
+            UnaryOperator<String> it = s -> interpolator.interpolate(s, cb);
             configuration = new ExtensionInterpolator(it).transform(configuration);
 
             binder.bind(XmlNode.class)
@@ -65,7 +65,7 @@ public void configure(Binder binder) {
     }
 
     static class ExtensionInterpolator extends MavenTransformer {
-        ExtensionInterpolator(Function<String, String> transformer) {
+        ExtensionInterpolator(UnaryOperator<String> transformer) {
             super(transformer);
         }
 

compat/maven-embedder/src/main/java/org/apache/maven/cli/MavenCli.java

@@ -45,7 +45,7 @@
 import java.util.ServiceLoader;
 import java.util.Set;
 import java.util.function.Consumer;
-import java.util.function.Function;
+import java.util.function.UnaryOperator;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 import java.util.stream.Stream;
@@ -643,7 +643,7 @@ void properties(CliRequest cliRequest) throws Exception {
         populateProperties(cliRequest.commandLine, paths, cliRequest.systemProperties, cliRequest.userProperties);
 
         // now that we have properties, interpolate all arguments
-        Function<String, String> callback = v -> {
+        UnaryOperator<String> callback = v -> {
             String r = paths.getProperty(v);
             if (r == null) {
                 r = cliRequest.systemProperties.getProperty(v);
@@ -724,7 +724,7 @@ protected void configure() {
 
         container.setLoggerManager(plexusLoggerManager);
 
-        Function<String, String> extensionSource = expression -> {
+        UnaryOperator<String> extensionSource = expression -> {
             String value = cliRequest.userProperties.getProperty(expression);
             if (value == null) {
                 value = cliRequest.systemProperties.getProperty(expression);
@@ -1660,7 +1660,7 @@ void populateProperties(
         // ----------------------------------------------------------------------
         // Load config files
         // ----------------------------------------------------------------------
-        Function<String, String> callback =
+        UnaryOperator<String> callback =
                 or(paths::getProperty, prefix("cli.", commandLine::getOptionValue), systemProperties::getProperty);
 
         Path mavenConf;
@@ -1686,7 +1686,7 @@ void populateProperties(
                 .forEach(k -> System.setProperty(k, userProperties.getProperty(k)));
     }
 
-    private static Function<String, String> prefix(String prefix, Function<String, String> cb) {
+    private static UnaryOperator<String> prefix(String prefix, UnaryOperator<String> cb) {
         return s -> {
             String v = null;
             if (s.startsWith(prefix)) {
@@ -1696,9 +1696,9 @@ private static Function<String, String> prefix(String prefix, Function<String, S
         };
     }
 
-    private static Function<String, String> or(Function<String, String>... callbacks) {
+    private static UnaryOperator<String> or(UnaryOperator<String>... callbacks) {
         return s -> {
-            for (Function<String, String> cb : callbacks) {
+            for (UnaryOperator<String> cb : callbacks) {
                 String r = cb.apply(s);
                 if (r != null) {
                     return r;

compat/maven-embedder/src/main/java/org/apache/maven/cli/internal/BootstrapCoreExtensionManager.java

@@ -27,7 +27,7 @@
 import java.util.List;
 import java.util.NoSuchElementException;
 import java.util.Set;
-import java.util.function.Function;
+import java.util.function.UnaryOperator;
 import java.util.stream.Collectors;
 
 import org.apache.maven.RepositoryUtils;
@@ -139,7 +139,7 @@ public List<CoreExtensionEntry> loadCoreExtensions(
             InternalSession.associate(repoSession, iSession);
 
             List<RemoteRepository> repositories = RepositoryUtils.toRepos(request.getPluginArtifactRepositories());
-            Function<String, String> interpolator = createInterpolator(request);
+            UnaryOperator<String> interpolator = createInterpolator(request);
 
             return resolveCoreExtensions(repoSession, repositories, providedArtifacts, extensions, interpolator);
         }
@@ -150,7 +150,7 @@ private List<CoreExtensionEntry> resolveCoreExtensions(
             List<RemoteRepository> repositories,
             Set<String> providedArtifacts,
             List<CoreExtension> configuration,
-            Function<String, String> interpolator)
+            UnaryOperator<String> interpolator)
             throws Exception {
         List<CoreExtensionEntry> extensions = new ArrayList<>();
 
@@ -208,7 +208,7 @@ private List<Artifact> resolveExtension(
             RepositorySystemSession repoSession,
             List<RemoteRepository> repositories,
             DependencyFilter dependencyFilter,
-            Function<String, String> interpolator)
+            UnaryOperator<String> interpolator)
             throws ExtensionResolutionException {
         try {
             /* TODO: Enhance the PluginDependenciesResolver to provide a
@@ -232,9 +232,9 @@ private List<Artifact> resolveExtension(
         }
     }
 
-    private static Function<String, String> createInterpolator(MavenExecutionRequest request) {
+    private static UnaryOperator<String> createInterpolator(MavenExecutionRequest request) {
         Interpolator interpolator = new DefaultInterpolator();
-        Function<String, String> callback = v -> {
+        UnaryOperator<String> callback = v -> {
             String r = request.getUserProperties().getProperty(v);
             if (r == null) {
                 r = request.getSystemProperties().getProperty(v);