Index: trunk/test/unit/org/openstreetmap/josm/actions/MergeLayerActionTest.java
===================================================================
--- trunk/test/unit/org/openstreetmap/josm/actions/MergeLayerActionTest.java	(revision 16158)
+++ trunk/test/unit/org/openstreetmap/josm/actions/MergeLayerActionTest.java	(revision 16159)
@@ -4,4 +4,6 @@
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNull;
+
+import java.util.Collections;
 
 import javax.swing.JLabel;
@@ -21,6 +23,4 @@
 import org.openstreetmap.josm.testutils.mockers.ExtendedDialogMocker;
 import org.openstreetmap.josm.testutils.mockers.JOptionPaneSimpleMocker;
-
-import com.google.common.collect.ImmutableMap;
 
 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
@@ -85,5 +85,5 @@
         TestUtils.assumeWorkingJMockit();
         final JOptionPaneSimpleMocker jopsMocker = new JOptionPaneSimpleMocker(
-            ImmutableMap.<String, Object>of("<html>There are no layers the source layer<br>'onion'<br>could be merged to.</html>", 0)
+            Collections.singletonMap("<html>There are no layers the source layer<br>'onion'<br>could be merged to.</html>", 0)
         );
 
Index: trunk/test/unit/org/openstreetmap/josm/gui/dialogs/changeset/ChangesetCacheManagerTest.java
===================================================================
--- trunk/test/unit/org/openstreetmap/josm/gui/dialogs/changeset/ChangesetCacheManagerTest.java	(revision 16158)
+++ trunk/test/unit/org/openstreetmap/josm/gui/dialogs/changeset/ChangesetCacheManagerTest.java	(revision 16159)
@@ -32,6 +32,4 @@
 import org.openstreetmap.josm.testutils.mockers.WindowMocker;
 
-import com.google.common.collect.ImmutableMap;
-
 import mockit.Invocation;
 import mockit.Mock;
@@ -122,5 +120,5 @@
         TestUtils.assumeWorkingJMockit();
         final HelpAwareOptionPaneMocker haMocker = new HelpAwareOptionPaneMocker(
-            ImmutableMap.<String, Object>of(
+            Collections.singletonMap(
                 "<html>JOSM is currently running with an anonymous user. It cannot download<br>"
                 + "your changesets from the OSM server unless you enter your OSM user name<br>"
Index: trunk/test/unit/org/openstreetmap/josm/gui/help/HelpBrowserTest.java
===================================================================
--- trunk/test/unit/org/openstreetmap/josm/gui/help/HelpBrowserTest.java	(revision 16158)
+++ trunk/test/unit/org/openstreetmap/josm/gui/help/HelpBrowserTest.java	(revision 16159)
@@ -4,4 +4,6 @@
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNull;
+
+import java.util.Collections;
 
 import javax.swing.JOptionPane;
@@ -16,6 +18,4 @@
 import org.openstreetmap.josm.tools.PlatformManager;
 
-import com.google.common.collect.ImmutableMap;
-
 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
 import mockit.Expectations;
@@ -157,5 +157,5 @@
         }};
         final JOptionPaneSimpleMocker jopsMocker = new JOptionPaneSimpleMocker(
-            ImmutableMap.<String, Object>of(
+            Collections.singletonMap(
                 "<html>The current URL <tt>https://josm.openstreetmap.de/javadoc</tt><br>is an external "
                 + "URL. Editing is only possible for help topics<br>on the help server "
Index: trunk/test/unit/org/openstreetmap/josm/gui/io/AsynchronousUploadPrimitivesTaskTest.java
===================================================================
--- trunk/test/unit/org/openstreetmap/josm/gui/io/AsynchronousUploadPrimitivesTaskTest.java	(revision 16158)
+++ trunk/test/unit/org/openstreetmap/josm/gui/io/AsynchronousUploadPrimitivesTaskTest.java	(revision 16159)
@@ -2,4 +2,5 @@
 package org.openstreetmap.josm.gui.io;
 
+import java.util.Collections;
 import java.util.Optional;
 
@@ -22,6 +23,4 @@
 import org.openstreetmap.josm.testutils.JOSMTestRules;
 import org.openstreetmap.josm.testutils.mockers.JOptionPaneSimpleMocker;
-
-import com.google.common.collect.ImmutableMap;
 
 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
@@ -90,5 +89,5 @@
     public void testSingleUploadInstance() {
         TestUtils.assumeWorkingJMockit();
-        new JOptionPaneSimpleMocker(ImmutableMap.of(
+        new JOptionPaneSimpleMocker(Collections.singletonMap(
                 "A background upload is already in progress. Kindly wait for it to finish before uploading new changes", JOptionPane.OK_OPTION
             ));
Index: trunk/test/unit/org/openstreetmap/josm/gui/io/DownloadOpenChangesetsTaskTest.java
===================================================================
--- trunk/test/unit/org/openstreetmap/josm/gui/io/DownloadOpenChangesetsTaskTest.java	(revision 16158)
+++ trunk/test/unit/org/openstreetmap/josm/gui/io/DownloadOpenChangesetsTaskTest.java	(revision 16159)
@@ -9,4 +9,5 @@
 import java.awt.GraphicsEnvironment;
 import java.net.URL;
+import java.util.Collections;
 
 import javax.swing.JOptionPane;
@@ -22,6 +23,4 @@
 import org.openstreetmap.josm.testutils.mockers.WindowMocker;
 import org.openstreetmap.josm.tools.UserCancelException;
-
-import com.google.common.collect.ImmutableMap;
 
 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
@@ -80,5 +79,5 @@
         final OAuthWizardMocker oaWizardMocker = new OAuthWizardMocker();
         final JOptionPaneSimpleMocker jopsMocker = new JOptionPaneSimpleMocker(
-            ImmutableMap.<String, Object>of(
+            Collections.singletonMap(
                 "<html>Could not retrieve the list of your open changesets because<br>JOSM does not know "
                 + "your identity.<br>You have either chosen to work anonymously or you are not "
@@ -113,5 +112,5 @@
         final OAuthWizardMocker oaWizardMocker = new OAuthWizardMocker();
         final JOptionPaneSimpleMocker jopsMocker = new JOptionPaneSimpleMocker(
-            ImmutableMap.<String, Object>of("There are no open changesets", JOptionPane.OK_OPTION)
+            Collections.singletonMap("There are no open changesets", JOptionPane.OK_OPTION)
         );
 
Index: trunk/test/unit/org/openstreetmap/josm/gui/layer/OsmDataLayerTest.java
===================================================================
--- trunk/test/unit/org/openstreetmap/josm/gui/layer/OsmDataLayerTest.java	(revision 16158)
+++ trunk/test/unit/org/openstreetmap/josm/gui/layer/OsmDataLayerTest.java	(revision 16159)
@@ -12,4 +12,5 @@
 import java.text.DateFormat;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.Iterator;
 
@@ -39,6 +40,4 @@
 import org.openstreetmap.josm.tools.Logging;
 import org.openstreetmap.josm.tools.date.DateUtils;
-
-import com.google.common.collect.ImmutableMap;
 
 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
@@ -295,5 +294,5 @@
         TestUtils.assumeWorkingJMockit();
         final ExtendedDialogMocker edMocker = new ExtendedDialogMocker(
-            ImmutableMap.<String, Object>of("The document contains no data.", "Cancel")
+            Collections.singletonMap("The document contains no data.", "Cancel")
         );
 
Index: trunk/test/unit/org/openstreetmap/josm/gui/layer/gpx/DownloadAlongTrackActionTest.java
===================================================================
--- trunk/test/unit/org/openstreetmap/josm/gui/layer/gpx/DownloadAlongTrackActionTest.java	(revision 16158)
+++ trunk/test/unit/org/openstreetmap/josm/gui/layer/gpx/DownloadAlongTrackActionTest.java	(revision 16159)
@@ -5,4 +5,6 @@
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
+
+import java.util.Collections;
 
 import org.junit.Rule;
@@ -17,6 +19,4 @@
 import org.openstreetmap.josm.testutils.JOSMTestRules;
 import org.openstreetmap.josm.testutils.mockers.HelpAwareOptionPaneMocker;
-
-import com.google.common.collect.ImmutableMap;
 
 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
@@ -36,5 +36,5 @@
     private static PleaseWaitRunnable createTask(String file) throws Exception {
         // click "Download" when presented with the appropriate HelpAwareOptionPane
-        final HelpAwareOptionPaneMocker haMocker = new HelpAwareOptionPaneMocker(ImmutableMap.of(
+        final HelpAwareOptionPaneMocker haMocker = new HelpAwareOptionPaneMocker(Collections.singletonMap(
             "DownloadAlongPanel", "Download"
         )) {
Index: trunk/test/unit/org/openstreetmap/josm/gui/layer/gpx/DownloadWmsAlongTrackActionTest.java
===================================================================
--- trunk/test/unit/org/openstreetmap/josm/gui/layer/gpx/DownloadWmsAlongTrackActionTest.java	(revision 16158)
+++ trunk/test/unit/org/openstreetmap/josm/gui/layer/gpx/DownloadWmsAlongTrackActionTest.java	(revision 16159)
@@ -7,4 +7,6 @@
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
+
+import java.util.Collections;
 
 import org.awaitility.Awaitility;
@@ -21,6 +23,4 @@
 import org.openstreetmap.josm.testutils.TileSourceRule;
 import org.openstreetmap.josm.testutils.mockers.JOptionPaneSimpleMocker;
-
-import com.google.common.collect.ImmutableMap;
 
 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
@@ -45,5 +45,5 @@
         TestUtils.assumeWorkingJMockit();
         final JOptionPaneSimpleMocker jopsMocker = new JOptionPaneSimpleMocker(
-            ImmutableMap.<String, Object>of("There are no imagery layers.", 0)
+            Collections.singletonMap("There are no imagery layers.", 0)
         );
 
Index: trunk/test/unit/org/openstreetmap/josm/gui/preferences/advanced/ExportProfileActionTest.java
===================================================================
--- trunk/test/unit/org/openstreetmap/josm/gui/preferences/advanced/ExportProfileActionTest.java	(revision 16158)
+++ trunk/test/unit/org/openstreetmap/josm/gui/preferences/advanced/ExportProfileActionTest.java	(revision 16159)
@@ -1,4 +1,6 @@
 // License: GPL. For details, see LICENSE file.
 package org.openstreetmap.josm.gui.preferences.advanced;
+
+import java.util.Collections;
 
 import javax.swing.JOptionPane;
@@ -10,6 +12,4 @@
 import org.openstreetmap.josm.testutils.JOSMTestRules;
 import org.openstreetmap.josm.testutils.mockers.JOptionPaneSimpleMocker;
-
-import com.google.common.collect.ImmutableMap;
 
 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
@@ -32,5 +32,5 @@
     public void testAction() {
         TestUtils.assumeWorkingJMockit();
-        new JOptionPaneSimpleMocker(ImmutableMap.of(
+        new JOptionPaneSimpleMocker(Collections.singletonMap(
             "All the preferences of this group are default, nothing to save", JOptionPane.OK_OPTION
         ));
Index: trunk/test/unit/org/openstreetmap/josm/gui/preferences/plugin/PluginPreferenceHighLevelTest.java
===================================================================
--- trunk/test/unit/org/openstreetmap/josm/gui/preferences/plugin/PluginPreferenceHighLevelTest.java	(revision 16158)
+++ trunk/test/unit/org/openstreetmap/josm/gui/preferences/plugin/PluginPreferenceHighLevelTest.java	(revision 16159)
@@ -12,4 +12,5 @@
 import java.nio.file.Files;
 import java.util.Collection;
+import java.util.Collections;
 
 import javax.swing.JOptionPane;
@@ -35,5 +36,4 @@
 import com.github.tomakehurst.wiremock.junit.WireMockRule;
 import com.google.common.collect.ImmutableList;
-import com.google.common.collect.ImmutableMap;
 
 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
@@ -137,5 +137,5 @@
             new PluginServer.RemotePlugin(this.referenceDummyJarNew),
             new PluginServer.RemotePlugin(this.referenceBazJarOld),
-            new PluginServer.RemotePlugin(null, ImmutableMap.of("Plugin-Version", "2"), "irrelevant_plugin")
+            new PluginServer.RemotePlugin(null, Collections.singletonMap("Plugin-Version", "2"), "irrelevant_plugin")
         );
         pluginServer.applyToWireMockServer(this.pluginServerRule);
@@ -143,5 +143,5 @@
 
         final HelpAwareOptionPaneMocker haMocker = new HelpAwareOptionPaneMocker(
-            ImmutableMap.<String, Object>of(
+            Collections.singletonMap(
                 "<html>The following plugin has been downloaded <strong>successfully</strong>:"
                 + "<ul><li>baz_plugin (6)</li></ul>"
@@ -268,5 +268,5 @@
 
         final HelpAwareOptionPaneMocker haMocker = new HelpAwareOptionPaneMocker(
-            ImmutableMap.<String, Object>of(
+            Collections.singletonMap(
                 "<html>You have to restart JOSM for some settings to take effect."
                 + "<br/><br/>Would you like to restart now?</html>",
@@ -581,5 +581,5 @@
             new PluginServer.RemotePlugin(this.referenceDummyJarOld),
             new PluginServer.RemotePlugin(this.referenceBazJarOld),
-            new PluginServer.RemotePlugin(null, ImmutableMap.of("Plugin-Version", "123"), "irrelevant_plugin")
+            new PluginServer.RemotePlugin(null, Collections.singletonMap("Plugin-Version", "123"), "irrelevant_plugin")
         );
         pluginServer.applyToWireMockServer(this.pluginServerRule);
@@ -587,5 +587,5 @@
 
         final HelpAwareOptionPaneMocker haMocker = new HelpAwareOptionPaneMocker(
-            ImmutableMap.<String, Object>of(
+            Collections.singletonMap(
                 "All installed plugins are up to date. JOSM does not have to download newer versions.",
                 "OK"
@@ -740,5 +740,5 @@
 
         final HelpAwareOptionPaneMocker haMocker = new HelpAwareOptionPaneMocker();
-        final JOptionPaneSimpleMocker jopsMocker = new JOptionPaneSimpleMocker(ImmutableMap.<String, Object>of(
+        final JOptionPaneSimpleMocker jopsMocker = new JOptionPaneSimpleMocker(Collections.singletonMap(
             "<html>The following plugin has been downloaded <strong>successfully</strong>:"
             + "<ul><li>dummy_plugin (31772)</li></ul></html>",
@@ -845,5 +845,5 @@
         final PluginServer pluginServer = new PluginServer(
             new PluginServer.RemotePlugin(this.referenceDummyJarNew),
-            new PluginServer.RemotePlugin(this.referenceBazJarNew, ImmutableMap.of(
+            new PluginServer.RemotePlugin(this.referenceBazJarNew, Collections.singletonMap(
                 "6800_Plugin-Url", "6;http://localhost:" + this.pluginServerRule.port() + bazOldServePath
             ))
@@ -860,5 +860,5 @@
         Config.getPref().putList("plugins", ImmutableList.of());
 
-        final HelpAwareOptionPaneMocker haMocker = new HelpAwareOptionPaneMocker(ImmutableMap.of(
+        final HelpAwareOptionPaneMocker haMocker = new HelpAwareOptionPaneMocker(Collections.singletonMap(
             "<html>The following plugin has been downloaded <strong>successfully</strong>:"
             + "<ul><li>baz_plugin (6)</li></ul>"
Index: trunk/test/unit/org/openstreetmap/josm/plugins/PluginHandlerJOSMTooOldTest.java
===================================================================
--- trunk/test/unit/org/openstreetmap/josm/plugins/PluginHandlerJOSMTooOldTest.java	(revision 16158)
+++ trunk/test/unit/org/openstreetmap/josm/plugins/PluginHandlerJOSMTooOldTest.java	(revision 16159)
@@ -10,4 +10,5 @@
 import java.io.IOException;
 import java.nio.file.Files;
+import java.util.Collections;
 import java.util.List;
 
@@ -254,7 +255,5 @@
         final PluginServer pluginServer = new PluginServer(
             new PluginServer.RemotePlugin(this.referenceDummyJarNew),
-            new PluginServer.RemotePlugin(this.referenceBazJarNew, ImmutableMap.of(
-                "Plugin-Mainversion", "5500"
-            ))
+            new PluginServer.RemotePlugin(this.referenceBazJarNew, Collections.singletonMap("Plugin-Mainversion", "5500"))
         );
         pluginServer.applyToWireMockServer(this.pluginServerRule);
@@ -312,5 +311,5 @@
         final PluginServer pluginServer = new PluginServer(
             new PluginServer.RemotePlugin(this.referenceBazJarOld),
-            new PluginServer.RemotePlugin(this.referenceQuxJarNewer, ImmutableMap.of(
+            new PluginServer.RemotePlugin(this.referenceQuxJarNewer, Collections.singletonMap(
                 "7499_Plugin-Url", "346;http://localhost:" + this.pluginServerRule.port() + "/dont/bother.jar"
             ))
@@ -319,5 +318,5 @@
         Config.getPref().putList("plugins", ImmutableList.of("qux_plugin", "baz_plugin"));
 
-        new ExtendedDialogMocker(ImmutableMap.of("JOSM version 7,500 required for plugin qux_plugin.", "Download Plugin"));
+        new ExtendedDialogMocker(Collections.singletonMap("JOSM version 7,500 required for plugin qux_plugin.", "Download Plugin"));
 
         Files.copy(this.referenceQuxJarOld.toPath(), this.targetQuxJar.toPath());
Index: trunk/test/unit/org/openstreetmap/josm/plugins/PluginHandlerTest.java
===================================================================
--- trunk/test/unit/org/openstreetmap/josm/plugins/PluginHandlerTest.java	(revision 16158)
+++ trunk/test/unit/org/openstreetmap/josm/plugins/PluginHandlerTest.java	(revision 16159)
@@ -9,4 +9,5 @@
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 import java.util.stream.Collectors;
@@ -27,6 +28,4 @@
 import org.openstreetmap.josm.testutils.mockers.HelpAwareOptionPaneMocker;
 import org.openstreetmap.josm.testutils.mockers.JOptionPaneSimpleMocker;
-
-import com.google.common.collect.ImmutableMap;
 
 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
@@ -104,5 +103,5 @@
         TestUtils.assumeWorkingJMockit();
         final JOptionPaneSimpleMocker jopsMocker = new JOptionPaneSimpleMocker(
-            ImmutableMap.<String, Object>of(
+            Collections.singletonMap(
                 "<html>The following plugin is no longer necessary and has been deactivated:" +
                     "<ul><li>imagery (integrated into main program)</li></ul></html>",
@@ -129,5 +128,5 @@
         TestUtils.assumeWorkingJMockit();
         final HelpAwareOptionPaneMocker haMocker = new HelpAwareOptionPaneMocker(
-            ImmutableMap.<String, Object>of(
+            Collections.singletonMap(
                 "<html>Loading of the plugin \"gpsbabelgui\" was requested.<br>" +
                     "This plugin is no longer developed and very likely will produce errors.<br>" +
