Troubleshooting HTTP 400 Bad Request errors on JBoss EAP 6

Issue

• We've had issues troubleshooting requests causing EAP to respond with an HTTP 400 Bad Request error.
• We found the cause to be the length of HTTP headers breaking MAX_HTTP_HEADER_SIZE. Here however we are concerned with the unexpected difficulty to identify the root cause.
• We attempted to use a RequestDumper valve, but this gave us no output in case of HTTP 400 Bad Request.
• We couldn't effectively use Byteman rules in the environment where we see the issues (it wasn't feasible for us to install required external jar files).
• We expected an easy way to troubleshoot the HTTP 400 Bad Request error, e.g. by enabling logging on the correct package and log level.