code: public boolean setAppVar(final String name, final String val,
                             final HashMap<String, String> appVars) {
      if (val == null) {
        appVars.remove(name);
        return true;
      }
  
      if (appVars.size() > maxAppVars) {
        return false;
      }
  
      appVars.put(name, val);
      return true;
    }
docs: Called to set an application variable to a value
  
  @param   name     name of variable
  @param   val      new value of variable - null means remove.
  @param appVars
  @return  boolean  True if ok - false for too many vars