[grid] Adding flag for undocumented node implementation

[skip ci]

Author: diemol

java/src/org/openqa/selenium/grid/node/config/NodeFlags.java

@@ -21,6 +21,7 @@
 import static org.openqa.selenium.grid.node.config.NodeOptions.DEFAULT_DETECT_DRIVERS;
 import static org.openqa.selenium.grid.node.config.NodeOptions.DEFAULT_HEARTBEAT_PERIOD;
 import static org.openqa.selenium.grid.node.config.NodeOptions.DEFAULT_MAX_SESSIONS;
+import static org.openqa.selenium.grid.node.config.NodeOptions.DEFAULT_NODE_IMPLEMENTATION;
 import static org.openqa.selenium.grid.node.config.NodeOptions.DEFAULT_REGISTER_CYCLE;
 import static org.openqa.selenium.grid.node.config.NodeOptions.DEFAULT_REGISTER_PERIOD;
 import static org.openqa.selenium.grid.node.config.NodeOptions.DEFAULT_SESSION_TIMEOUT;
@@ -42,7 +43,7 @@
 import java.util.List;
 import java.util.Set;
 
-@SuppressWarnings("unused")
+@SuppressWarnings({"unused", "FieldMayBeFinal"})
 @AutoService(HasRoles.class)
 public class NodeFlags implements HasRoles {
 
@@ -180,6 +181,14 @@ public class NodeFlags implements HasRoles {
   @ConfigValue(section = NODE_SECTION, name = "vnc-env-var", example = "START_XVFB")
   public String vncEnvVar = DEFAULT_VNC_ENV_VAR;
 
+  @Parameter(
+    names = {"--node-implementation"},
+    description = "Full classname of non-default Node implementation. This is used to manage "
+                  + "a session's lifecycle.")
+  @ConfigValue(section = NODE_SECTION, name = "implementation",
+    example = DEFAULT_NODE_IMPLEMENTATION)
+  private String nodeImplementation = DEFAULT_NODE_IMPLEMENTATION;
+
   @Override
   public Set<Role> getRoles() {
     return Collections.singleton(NODE_ROLE);

java/src/org/openqa/selenium/grid/node/config/NodeOptions.java

@@ -75,10 +75,10 @@ public class NodeOptions {
   static final String DEFAULT_VNC_ENV_VAR = "START_XVFB";
   static final int DEFAULT_REGISTER_CYCLE = 10;
   static final int DEFAULT_REGISTER_PERIOD = 120;
-
+  static final String DEFAULT_NODE_IMPLEMENTATION =
+    "org.openqa.selenium.grid.node.local.LocalNodeFactory";
   private static final Logger LOG = Logger.getLogger(NodeOptions.class.getName());
   private static final Json JSON = new Json();
-  private static final String DEFAULT_IMPL = "org.openqa.selenium.grid.node.local.LocalNodeFactory";
   private static final Platform CURRENT_PLATFORM = Platform.getCurrent();
   private static final ImmutableSet<String>
     SINGLE_SESSION_DRIVERS = ImmutableSet.of("safari", "safari technology preview");
@@ -145,7 +145,7 @@ public Optional<URI> getPublicGridUri() {
   }
 
   public Node getNode() {
-    return config.getClass(NODE_SECTION, "implementation", Node.class, DEFAULT_IMPL);
+    return config.getClass(NODE_SECTION, "implementation", Node.class, DEFAULT_NODE_IMPLEMENTATION);
   }
 
   public Duration getRegisterCycle() {