Add subgroup location for private namespace params

Rewrite comment with lookup order pattern

moveit_core/kinematics_base/include/moveit/kinematics_base/kinematics_base.h

@@ -602,17 +602,27 @@ class KinematicsBase
 
   /**
    * @brief Enables kinematics plugins access to parameters that are defined
-   * for the 'robot_description_kinematics' namespace.
-   * Parameters are queried in order of the specified group hierarchy.
-   * That is parameters are first searched in the private namespace
-   * then in the subroup namespace and finally in the group namespace.
+   * for the private namespace and inside 'robot_description_kinematics'.
+   * Parameters are searched in the following locations and order
+   *
+   * ~/<group_name>/<param>
+   * ~/<param>
+   * robot_description_kinematics/<group_name>/<param>
+   * robot_description_kinematics/<param>
+   *
    * This order maintains default behavior by keeping the private namespace
    * as the predominant configuration but also allows groupwise specifications.
    */
   template <typename T>
   inline bool lookupParam(const std::string& param, T& val, const T& default_val) const
   {
     ros::NodeHandle pnh("~");
+    if (pnh.hasParam(group_name_ + "/" + param))
+    {
+      val = pnh.param(group_name_ + "/" + param, default_val);
+      return true;
+    }
+
     if (pnh.hasParam(param))
     {
       val = pnh.param(param, default_val);