also fix priortizer

java/server/src/org/openqa/grid/internal/utils/configuration/GridHubConfiguration.java

@@ -32,7 +32,7 @@
 import org.openqa.grid.internal.listeners.Prioritizer;
 import org.openqa.grid.internal.utils.CapabilityMatcher;
 import org.openqa.grid.internal.utils.DefaultCapabilityMatcher;
-import org.openqa.grid.internal.utils.configuration.converters.CapabilityMatcherStringConverter;
+import org.openqa.grid.internal.utils.configuration.converters.StringToClassConverter;
 import org.openqa.grid.internal.utils.configuration.validators.FileExistsValueValidator;
 
 import java.io.IOException;
@@ -60,7 +60,7 @@ public class GridHubConfiguration extends GridConfiguration {
   @Parameter(
     names = { "-matcher", "-capabilityMatcher" },
     description = "<String> class name : a class implementing the CapabilityMatcher interface. Specifies the logic the hub will follow to define whether a request can be assigned to a node. For example, if you want to have the matching process use regular expressions instead of exact match when specifying browser version. ALL nodes of a grid ecosystem would then use the same capabilityMatcher, as defined here. Default is org.openqa.grid.internal.utils.DefaultCapabilityMatcher",
-    converter = CapabilityMatcherStringConverter.class
+    converter = StringToClassConverter.CapabilityMatcherStringConverter.class
   )
   public CapabilityMatcher capabilityMatcher = new DefaultCapabilityMatcher();
 
@@ -75,7 +75,7 @@ public class GridHubConfiguration extends GridConfiguration {
   @Parameter(
     names = "-prioritizer",
     description = "<String> class name : a class implementing the Prioritizer interface. Specify a custom Prioritizer if you want to sort the order in which new session requests are processed when there is a queue. Default to null ( no priority = FIFO )",
-    converter = PrioritizerString.class
+    converter = StringToClassConverter.PrioritizerStringConverter.class
   )
   public Prioritizer prioritizer = null;
 
@@ -119,18 +119,6 @@ public static GridHubConfiguration loadFromJSON(JsonObject json) {
     }
   }
 
-  private class PrioritizerString implements IStringConverter<Prioritizer> {
-    @Override
-    public Prioritizer convert(String prioritizerClass) {
-      try {
-        return (Prioritizer) Class.forName(prioritizerClass).newInstance();
-      } catch (Throwable e) {
-        throw new GridConfigurationException("Error creating Prioritizer from class " +
-                                             prioritizerClass + " : " + e.getMessage(), e);
-      }
-    }
-  }
-
   public void merge(GridNodeConfiguration other) {
     super.merge(other);
   }

java/server/src/org/openqa/grid/internal/utils/configuration/converters/CapabilityMatcherStringConverter.java → java/server/src/org/openqa/grid/internal/utils/configuration/converters/StringToClassConverter.java

@@ -20,16 +20,21 @@
 import com.beust.jcommander.IStringConverter;
 
 import org.openqa.grid.common.exception.GridConfigurationException;
+import org.openqa.grid.internal.listeners.Prioritizer;
 import org.openqa.grid.internal.utils.CapabilityMatcher;
 
-public class CapabilityMatcherStringConverter implements IStringConverter<CapabilityMatcher> {
-  @Override
-  public CapabilityMatcher convert(String capabilityMatcherClass) {
+public abstract class StringToClassConverter<E> {
+  public E convert(String capabilityMatcherClass) {
     try {
-      return (CapabilityMatcher) Class.forName(capabilityMatcherClass).newInstance();
+      return (E) Class.forName(capabilityMatcherClass).newInstance();
     } catch (Throwable e) {
-      throw new GridConfigurationException("Error creating Prioritizer from class " +
+      throw new GridConfigurationException("Error creating class with " +
                                            capabilityMatcherClass + " : " + e.getMessage(), e);
     }
   }
+
+  public static class CapabilityMatcherStringConverter extends StringToClassConverter<CapabilityMatcher> implements IStringConverter<CapabilityMatcher>{}
+
+  public static class PrioritizerStringConverter extends StringToClassConverter<Prioritizer> implements IStringConverter<Prioritizer>{}
+
 }

java/server/test/org/openqa/grid/internal/utils/configuration/GridHubConfigurationTest.java

@@ -142,10 +142,13 @@ public void testToString() {
 
   @Test
   public void testJcommanderConverterCapabilityMatcher() {
-    String[] hubArgs = {"-role", "hub", "-capabilityMatcher", "org.openqa.grid.internal.utils.DefaultCapabilityMatcher"};
+    String[] hubArgs = {"-capabilityMatcher", "org.openqa.grid.internal.utils.DefaultCapabilityMatcher",
+                        "-prioritizer", "org.openqa.grid.internal.utils.configuration.PlaceHolderTestingPrioritizer"};
     GridHubConfiguration ghc = new GridHubConfiguration();
     new JCommander(ghc, hubArgs);
     assertEquals("org.openqa.grid.internal.utils.DefaultCapabilityMatcher",
                  ghc.capabilityMatcher.getClass().getCanonicalName());
+    assertEquals("org.openqa.grid.internal.utils.configuration.PlaceHolderTestingPrioritizer",
+                 ghc.prioritizer.getClass().getCanonicalName());
   }
 }

java/server/test/org/openqa/grid/internal/utils/configuration/PlaceHolderTestingPrioritizer.java

@@ -0,0 +1,29 @@
+// Licensed to the Software Freedom Conservancy (SFC) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The SFC licenses this file
+// to you 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 org.openqa.grid.internal.utils.configuration;
+
+import org.openqa.grid.internal.listeners.Prioritizer;
+
+import java.util.Map;
+
+public class PlaceHolderTestingPrioritizer implements Prioritizer {
+  @Override
+  public int compareTo(Map<String, Object> a, Map<String, Object> b) {
+    return 0;
+  }
+}