Index: trunk/test/functional/org/openstreetmap/josm/io/MultiFetchServerObjectReaderTest.java
===================================================================
--- trunk/test/functional/org/openstreetmap/josm/io/MultiFetchServerObjectReaderTest.java	(revision 15716)
+++ trunk/test/functional/org/openstreetmap/josm/io/MultiFetchServerObjectReaderTest.java	(revision 15717)
@@ -18,6 +18,8 @@
 import java.text.MessageFormat;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Locale;
 import java.util.Random;
+import java.util.TreeSet;
 import java.util.logging.Logger;
 
@@ -35,4 +37,5 @@
 import org.openstreetmap.josm.data.osm.Node;
 import org.openstreetmap.josm.data.osm.OsmPrimitive;
+import org.openstreetmap.josm.data.osm.OsmPrimitiveType;
 import org.openstreetmap.josm.data.osm.Relation;
 import org.openstreetmap.josm.data.osm.RelationMember;
@@ -42,4 +45,5 @@
 
 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
+import org.openstreetmap.josm.testutils.JOSMTestRules;
 
 /**
@@ -49,4 +53,11 @@
 public class MultiFetchServerObjectReaderTest {
     private static Logger logger = Logger.getLogger(MultiFetchServerObjectReader.class.getName());
+
+    /**
+     * Setup test.
+     */
+    @Rule
+    @SuppressFBWarnings(value = "URF_UNREAD_PUBLIC_OR_PROTECTED_FIELD")
+    public JOSMTestRules test = new JOSMTestRules().preferences();
 
     /**
@@ -332,3 +343,13 @@
         assertEquals(9999999, reader.getMissingPrimitives().iterator().next().getUniqueId());
     }
+
+    /**
+     * Test {@link MultiFetchServerObjectReader#buildRequestString}
+     */
+    @Test
+    public void testBuildRequestString() {
+        String requestString = new MultiFetchServerObjectReader()
+                .buildRequestString(OsmPrimitiveType.WAY, new TreeSet<>(Arrays.asList(130L, 123L, 126L)));
+        assertEquals("ways?ways=123,126,130", requestString);
+    }
 }
Index: trunk/test/unit/org/openstreetmap/josm/io/MultiFetchOverpassObjectReaderTest.java
===================================================================
--- trunk/test/unit/org/openstreetmap/josm/io/MultiFetchOverpassObjectReaderTest.java	(revision 15717)
+++ trunk/test/unit/org/openstreetmap/josm/io/MultiFetchOverpassObjectReaderTest.java	(revision 15717)
@@ -0,0 +1,38 @@
+// License: GPL. For details, see LICENSE file.
+package org.openstreetmap.josm.io;
+
+import static org.junit.Assert.assertEquals;
+
+import java.util.Arrays;
+import java.util.TreeSet;
+
+import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
+import org.junit.Rule;
+import org.junit.Test;
+import org.openstreetmap.josm.data.osm.OsmPrimitiveType;
+import org.openstreetmap.josm.testutils.JOSMTestRules;
+import org.openstreetmap.josm.tools.Utils;
+
+/**
+ * Unit tests of {@link MultiFetchOverpassObjectReader}.
+ */
+public class MultiFetchOverpassObjectReaderTest {
+
+    /**
+     * Setup test.
+     */
+    @Rule
+    @SuppressFBWarnings(value = "URF_UNREAD_PUBLIC_OR_PROTECTED_FIELD")
+    public JOSMTestRules test = new JOSMTestRules().preferences();
+
+    /**
+     * Test {@link MultiFetchOverpassObjectReader#buildRequestString}
+     */
+    @Test
+    public void testBuildRequestString() {
+        String requestString = new MultiFetchOverpassObjectReader()
+                .buildRequestString(OsmPrimitiveType.WAY, new TreeSet<>(Arrays.asList(130L, 123L, 126L)));
+        assertEquals("interpreter?data=" + Utils.encodeUrl("(way(123);>;way(126);>;way(130);>;);out meta;"), requestString);
+    }
+
+}
Index: trunk/test/unit/org/openstreetmap/josm/plugins/PluginHandlerTest.java
===================================================================
--- trunk/test/unit/org/openstreetmap/josm/plugins/PluginHandlerTest.java	(revision 15716)
+++ trunk/test/unit/org/openstreetmap/josm/plugins/PluginHandlerTest.java	(revision 15717)
@@ -10,4 +10,6 @@
 import java.util.Arrays;
 import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 import javax.swing.JScrollPane;
@@ -24,6 +26,4 @@
 import org.openstreetmap.josm.testutils.mockers.HelpAwareOptionPaneMocker;
 import org.openstreetmap.josm.testutils.mockers.JOptionPaneSimpleMocker;
-import org.openstreetmap.josm.tools.Utils;
-
 import com.google.common.collect.ImmutableMap;
 
@@ -70,7 +70,9 @@
         final String old = System.getProperty("josm.plugins");
         try {
-            System.setProperty("josm.plugins",
-                    Utils.join(",", PluginHandler.DEPRECATED_PLUGINS) + "," +
-                    Utils.join(",", Arrays.asList(PluginHandler.UNMAINTAINED_PLUGINS)));
+            final String plugins = Stream.concat(
+                    PluginHandler.DEPRECATED_PLUGINS.stream(),
+                    PluginHandler.UNMAINTAINED_PLUGINS.stream()
+            ).map(String::valueOf).collect(Collectors.joining(","));
+            System.setProperty("josm.plugins", plugins);
             List<PluginInformation> list = PluginHandler.buildListOfPluginsToLoad(null, null);
             assertNotNull(list);