Provide CommandExecutorAdapter

User Story (Required on creation):

As a process application developer, I want to be able to execute Camunda Commands outside of a Camunda initiated context transaction.

Functional Requirements (Required before implementation):

Being able to execute commands arbitrary from the thread local context.

Technical Requirements (Required before implementation):

Provide an Adapter interface that can either execute on Context or Executor.

I have been using this frequently in various projects and came up with this solution (see hint). I would love to have this in the engine core so I do not have to re-invent it for every project.

Hints (Optional):

/**
{{ * Adapter that hides the execution of a camunda {@link Command}, works with {@link org.camunda.bpm.engine.impl.interceptor.CommandContext} when called inside}}
{{ * a camunda {@link org.camunda.bpm.engine.delegate.JavaDelegate} or Listener but uses {@link ProcessEngineConfigurationImpl#getCommandExecutorTxRequired()}}}
{{ * to get a new context when called elsewhere.}}
{{ */}}
public interface CommandExecutorAdapter {

static CommandExecutorAdapter create(CommandContext commandContext) {
    return new CommandExecutorAdapter() {
        @Override
        public <T> T execute(Command<T> command) {
            return command.execute(commandContext);
{{        }}}
    };
{{ }}}

static CommandExecutorAdapter create(ProcessEngineConfigurationImpl configuration) {
       return new CommandExecutorAdapter() {
          @Override
          public <T> T execute(Command<T> command) {
              if (Context.getCommandContext() == null) {
                 return configuration.getCommandExecutorTxRequired().execute(command);
              } else {
                  return command.execute(Context.getCommandContext());
{{              }}}
         }
     };
{{  }}}

  <T> T execute(Command<T> command);
}