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# Type of request: This is a bug report

# Detailed description
When running a java lambda in localstack with `LAMBDA_EXECUTOR=docker` and  `LAMBDA_JAVA_OPTS="-agentlib:jdwp=transport=dt_socket,server=y,suspend=y,address=5005"` (replaced `_debug_port_` with `5005`), the port is not opened in the lambda execution docker container.

Looking at `Util.get_java_opts` in `localstack/services/awslambda/lambda_executors.py`, `debug_java_port` is not set in case `_debug_port_` is set

```
class Util:
    debug_java_port = False

    @classmethod
    def get_java_opts(cls):
        opts = config.LAMBDA_JAVA_OPTS or ''
        if '_debug_port_' in opts:
            if not cls.debug_java_port:
                cls.debug_java_port = get_free_tcp_port() ### <<< debug_java_port is only set here
            opts = opts.replace('_debug_port_', ('%s' % cls.debug_java_port))
        ### In other case, `cls.debug_java_port` is not set.
        return opts
```
## Expected behavior

`debug_java_port` should be set to the configured port

## Actual behavior

`debug_java_port` is empty

# Steps to reproduce
docker-compose file
```
version: '2.1'
services:
  localstack:
    container_name: localstack
    image: localstack/localstack
    privileged: true
    ports:
      - "4567-4582:4567-4582"
      - "9070:9070"
    environment:
      SERVICES: sqs,lambda
      DOCKER_HOST: unix:///var/run/docker.sock
      PORT_WEB_UI: 9070
      LAMBDA_EXECUTOR: docker
      LAMBDA_JAVA_OPTS: "-agentlib:jdwp=transport=dt_socket,server=y,suspend=y,address=5005"
      DEBUG: 1
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
      - /tmp/localstack:/tmp/localstack
```

## Command used to start LocalStack

`docker-compose up`


pass
    def cleanup(self, arn=None):
        pass
    def run_lambda_executor(self, cmd, event=None, func_details=None, env_vars={}):
        process = run(cmd, asynchronous=True, stderr=subprocess.PIPE, outfile=subprocess.PIPE,
                      env_vars=env_vars, stdin=True)
        result, log_output = process.communicate(input=event)
        try:
            result = to_str(result).strip()
        except Exception:
            pass
        log_output = to_str(log_output).strip()
        return_code = process.returncode
        
        
        
        if isinstance(result, six.string_types) and '\n' in result:
            additional_logs, _, result = result.rpartition('\n')
            log_output += '\n%s' % additional_logs
        log_formatted = log_output.strip().replace('\n', '\n> ')
        func_arn = func_details and func_details.arn()
        LOG.debug('Lambda %s result / log output:\n%s\n> %s' % (func_arn, result.strip(), log_formatted))
        
        _store_logs(func_details, log_output)
        if return_code != 0:
            raise Exception('Lambda process returned error status code: %s. Result: %s. Output:\n%s' %
                (return_code, result, log_output))
        return result
class ContainerInfo: