Delegate dynamicBeans for external plugins

When dynamicbeans are defined by an external plugin on commands from a
different plugin, instantiate the dynamic bean with a delegating
classloader which uses the command's classloader as the parent and
resolves resources via the dynamicbean's classloader.  Also instantiate
the dynamicbeans using the injector from the command.

Change-Id: If2cff8235a9680eb64c58b77f2d482c5896baf0f

gerrit-httpd/src/main/java/com/google/gerrit/httpd/restapi/ParameterParser.java

@@ -36,6 +36,7 @@ import com.google.gson.JsonObject;
 import com.google.gson.JsonPrimitive;
 import com.google.gwtexpui.server.CacheHeaders;
 import com.google.inject.Inject;
+import com.google.inject.Injector;
 import java.io.IOException;
 import java.io.StringWriter;
 import java.util.HashSet;
@@ -51,11 +52,16 @@ class ParameterParser {
       ImmutableSet.of("pp", "prettyPrint", "strict", "callback", "alt", "fields");
 
   private final CmdLineParser.Factory parserFactory;
+  private final Injector injector;
   private final DynamicMap<DynamicOptions.DynamicBean> dynamicBeans;
 
   @Inject
-  ParameterParser(CmdLineParser.Factory pf, DynamicMap<DynamicOptions.DynamicBean> dynamicBeans) {
+  ParameterParser(
+      CmdLineParser.Factory pf,
+      Injector injector,
+      DynamicMap<DynamicOptions.DynamicBean> dynamicBeans) {
     this.parserFactory = pf;
+    this.injector = injector;
     this.dynamicBeans = dynamicBeans;
   }
 
@@ -63,7 +69,7 @@ class ParameterParser {
       T param, ListMultimap<String, String> in, HttpServletRequest req, HttpServletResponse res)
       throws IOException {
     CmdLineParser clp = parserFactory.create(param);
-    DynamicOptions pluginOptions = new DynamicOptions(param, dynamicBeans);
+    DynamicOptions pluginOptions = new DynamicOptions(param, injector, dynamicBeans);
     pluginOptions.parseDynamicBeans(clp);
     pluginOptions.setDynamicBeans();
     pluginOptions.onBeanParseStart();