You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: java_thread_pool_executor.rb
    path of file: ./repos/brew/Library/Homebrew/vendor/bundle-standalone/ruby/2.3.0/gems/concurrent-ruby-1.1.4/lib/concurrent/executor
    
    the code of the file until where you have to start completion: if Concurrent.on_jruby?

  require 'concurrent/executor/java_executor_service'

  module Concurrent

    # @!macro thread_pool_executor
    # @!macro thread_pool_options
    # @!visibility private
    class JavaThreadPoolExecutor < JavaExecutorService

      # @!macro thread_pool_executor_constant_default_max_pool_size
      DEFAULT_MAX_POOL_SIZE = java.lang.Integer::MAX_VALUE # 2147483647

      # @!macro thread_pool_executor_constant_default_min_pool_size
      DEFAULT_MIN_POOL_SIZE = 0

      # @!macro thread_pool_executor_constant_default
    
      def ns_initialize(opts)
        min_length       = opts.fetch(:min_threads, DEFAULT_MIN_POOL_SIZE).to_i
        max_length       = opts.fetch(:max_threads, DEFAULT_MAX_POOL_SIZE).to_i
        idletime         = opts.fetch(:idletime, DEFAULT_THREAD_IDLETIMEOUT).to_i
        @max_queue       = opts.fetch(:max_queue, DEFAULT_MAX_QUEUE_SIZE).to_i
        @fallback_policy = opts.fetch(:fallback_policy, :abort)

        raise ArgumentError.new("`max_threads` cannot be less than #{DEFAULT_MIN_POOL_SIZE}") if max_length < DEFAULT_MIN_POOL_SIZE
        raise ArgumentError.new("`max_threads` cannot be greater than #{DEFAULT_MAX_POOL_SIZE}") if max_length > DEFAULT_MAX_POOL_SIZE
        raise ArgumentError.new("`min_threads` cannot be less than #{DEFAULT_MIN_POOL_SIZE}") if min_length < DEFAULT_MIN_POOL_SIZE
        raise ArgumentError.new("`min_threads` cannot be more than `max_threads`") if min_length > max_length
        raise ArgumentError.new("#{fallback_policy} is not a valid fallback policy") unless FALLBACK_POLICY_CLASSES.include?(@fallback_policy)

        if @max_queue == 0
          queue = java.util.concurrent.LinkedBlockingQueue.new
        else
          queue = java.util.concurrent.LinkedBlockingQueue.new(@max_queue)
        end