Bootstrap class plugins

All bootstrap plugins are optional, due to unexpected risk. Bootstrap plugins are provided in bootstrap-plugins folder. For using these plugins, you need to put the target plugin jar file into /plugins.

Now, we have the following known bootstrap plugins.

• Plugin of JDK HttpURLConnection. Agent is compatible with JDK 1.8+
• Plugin of JDK Callable and Runnable. Agent is compatible with JDK 1.8+
• Plugin of JDK ThreadPoolExecutor. Agent is compatible with JDK 1.8+