code: public CallActivityMock onExecutionAddVariables(final VariableMap variables){
      return this.onExecutionDo("addVariablesServiceMock_"+ randomUUID(),
        (execution) -> variables.forEach(execution::setVariable)
      );
    }
docs: On execution, the MockProcess will add the given VariableMap to the execution
  
  @param variables the variables to add
  @return self