issue #1834: Refactor to Replace Guava with JDK Built-In Functionalities

src/main/java/io/fabric8/maven/docker/AbstractDockerMojo.java

@@ -3,14 +3,15 @@
 import java.io.File;
 import java.io.IOException;
 import java.util.Date;
+import java.util.Collections;
 import java.util.List;
+import java.util.ArrayList;
 import java.util.Map;
 import java.util.Properties;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 import java.util.stream.Collectors;
 
-import com.google.common.collect.ImmutableList;
 import io.fabric8.maven.docker.access.DockerAccess;
 import io.fabric8.maven.docker.access.DockerAccessException;
 import io.fabric8.maven.docker.access.ExecException;
@@ -501,8 +502,9 @@ protected LogDispatcher getLogDispatcher(ServiceHub hub) {
         return dispatcher;
     }
 
-    private ImmutableList<ImageConfiguration> getAllImages() {
-        ImmutableList.Builder<ImageConfiguration> allImages = ImmutableList.builder();
+    private List<ImageConfiguration> getAllImages() {
+        List<ImageConfiguration> allImages = new ArrayList<>();
+
         if (images != null) {
             allImages.addAll(images);
         }
@@ -514,7 +516,7 @@ private ImmutableList<ImageConfiguration> getAllImages() {
                 allImages.add(config);
             });
         }
-        return allImages.build();
+        return Collections.unmodifiableList(allImages);
     }
 
     public ImagePullManager getImagePullManager(String imagePullPolicy, String autoPull) {

src/main/java/io/fabric8/maven/docker/util/ContainerNamingUtil.java

@@ -1,15 +1,9 @@
 package io.fabric8.maven.docker.util;
 
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.Date;
-import java.util.HashMap;
-import java.util.Map;
-import java.util.Set;
+import java.util.*;
 import java.util.function.Function;
 import java.util.stream.Collectors;
 
-import com.google.common.collect.ImmutableSet;
 import io.fabric8.maven.docker.config.ImageConfiguration;
 import io.fabric8.maven.docker.config.RunImageConfiguration;
 import io.fabric8.maven.docker.model.Container;
@@ -164,11 +158,12 @@ private static Collection<Container> keepOnlyLastIndexedContainer(Collection<Con
     }
 
     private static Set<String> extractContainerNames(final Collection<Container> existingContainers) {
-        final ImmutableSet.Builder<String> containerNamesBuilder = ImmutableSet.builder();
+        final Set<String> containerNamesBuilder = new HashSet<>();
         for (final Container container : existingContainers) {
             containerNamesBuilder.add(container.getName());
         }
-        return containerNamesBuilder.build();
+
+        return Collections.unmodifiableSet(containerNamesBuilder);
     }
 
     private static String extractContainerNamePattern(ImageConfiguration image, String defaultContainerNamePattern) {

src/main/java/io/fabric8/maven/docker/util/CredentialHelperClient.java

@@ -1,12 +1,11 @@
 package io.fabric8.maven.docker.util;
 
-import com.google.common.base.Joiner;
-import com.google.common.collect.Lists;
 import com.google.gson.JsonObject;
 
 import org.apache.maven.plugin.MojoExecutionException;
 
 import java.io.IOException;
+import java.util.LinkedList;
 import java.util.List;
 
 import io.fabric8.maven.docker.access.AuthConfig;
@@ -93,7 +92,7 @@ public String getVersion() throws IOException {
     // echo <registryToLookup> | docker-credential-XXX get
     private class GetCommand extends ExternalCommand {
 
-        private List<String> reply = Lists.newLinkedList();
+        private final List<String> reply = new LinkedList<>();
 
         GetCommand() {
             super(CredentialHelperClient.this.log);
@@ -119,9 +118,10 @@ public JsonObject getCredentialNode(String registryToLookup) throws IOException
                     throw ex;
                 }
             }
-            JsonObject credentials = JsonFactory.newJsonObject(Joiner.on('\n').join(reply));
+            String joinedReply = String.join("\n", reply);
+            JsonObject credentials = JsonFactory.newJsonObject(joinedReply);
             if (!credentials.has(SECRET_KEY) || !credentials.has(USERNAME_KEY)) {
-                return null;
+                return null;  // If keys are missing, return null
             }
             return credentials;
         }

src/main/java/io/fabric8/maven/docker/util/ImageNameFormatter.java

@@ -20,8 +20,8 @@
 import java.util.Date;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.Objects;
 
-import com.google.common.base.Strings;
 import io.fabric8.maven.docker.config.ConfigHelper;
 import org.apache.maven.project.MavenProject;
 
@@ -178,7 +178,7 @@ public String doTransform(String tag, Date now) {
 
             public String transform(MavenProject project, String tag, Date now) {
                 // In case the Maven property is also a placeholder, replace it as well
-                if (Strings.isNullOrEmpty(tag) || tag.equals("%" + letter)) {
+                if(isNullorEmpty(tag) || tag.equals("%" + letter)) {
                     tag = project.getVersion();
                 }
                 return doTransform(tag, now);
@@ -248,4 +248,8 @@ private static String sanitizeName(String name) {
         // All characters must be lowercase
         return ret.toString().toLowerCase();
     }
+
+    private static boolean isNullorEmpty(String s) {
+        return Objects.isNull(s) || s.isEmpty();
+    }
 }

src/main/java/io/fabric8/maven/docker/util/JibServiceUtil.java

@@ -20,7 +20,6 @@
 import io.fabric8.maven.docker.config.Arguments;
 import io.fabric8.maven.docker.config.BuildImageConfiguration;
 import io.fabric8.maven.docker.config.ImageConfiguration;
-import io.fabric8.maven.docker.model.Image;
 import org.apache.commons.lang3.StringUtils;
 
 import java.io.File;