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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`


def test_get_java_lib_folder_classpath_archive_is_None(self):
        self.assertRaises(TypeError, lambda_executors.Util.get_java_classpath, None)
    @mock.patch('localstack.services.awslambda.lambda_executors.store_cloudwatch_logs')
    def test_executor_store_logs_can_handle_milliseconds(self, mock_store_cloudwatch_logs):
        mock_details = mock.Mock()
        t_sec = time.time()  
        t_ms = time.time() * 1000  
        
        lambda_executors._store_logs(mock_details, 'mock log output', t_ms)
        
        today = datetime.datetime.utcfromtimestamp(t_sec).strftime('%Y/%m/%d')
        log_stream_name = mock_store_cloudwatch_logs.call_args_list[0].args[1]
        parts = log_stream_name.split('/')
        date_part = '/'.join(parts[:3])
        self.assertEqual(date_part, today)
    def _create_function(self, function_name, tags={}):
        arn = lambda_api.func_arn(function_name)
        lambda_api.arn_to_lambda[arn] = LambdaFunction(arn)
        lambda_api.arn_to_lambda[arn].versions = {
            '$LATEST': {'CodeSize': self.CODE_SIZE, 'CodeSha256': self.CODE_SHA_256, 'RevisionId': self.REVISION_ID}
        }
        lambda_api.arn_to_lambda[arn].handler = self.HANDLER
        lambda_api.arn_to_lambda[arn].runtime = self.RUNTIME
        lambda_api.arn_to_lambda[arn].timeout = self.TIMEOUT
        lambda_api.arn_to_lambda[arn].tags = tags
        lambda_api.arn_to_lambda[arn].envvars = {}
        lambda_api.arn_to_lambda[arn].last_modified = self.LAST_MODIFIED
        lambda_api.arn_to_lambda[arn].role = self.ROLE
        lambda_api.arn_to_lambda[arn].memory_size = self.MEMORY_SIZE