hello, I tried with latest cf/diego release.
I still can reproduce the issue.
I am using all things provided by CF without any customization.
I just push my servlet APP and access it from command line.(You can find it in a previous reply in this thread)

wget http://test.[APP domain]/test
--2016-05-02 03:28:15-- http://test.[APP domain]/test
Resolving test.[APP domain] (test.[APP domain])... 152.190.109.xx
Connecting to test.[APP domain] (test.[APP domain])|152.190.109.xx|:80... connected.
HTTP request sent, awaiting response... 414 Request URI Too Long
2016-05-02 03:28:15 ERROR 414: Request URI Too Long.

Here the error message is "Request URI Too Long", which is the standard one, but my customized message "my customized 414 error message".


+---------------------------------------------+---------------+---------+--------------------------------------+
| Name | OS | Version | CID |
+---------------------------------------------+---------------+---------+--------------------------------------+
| bosh-warden-boshlite-ubuntu-trusty-go_agent | ubuntu-trusty | 3147* | 0636a704-8ac9-44a8-7f21-793f17310298 |
+---------------------------------------------+---------------+---------+--------------------------------------+

+-------------------+-----------------+-------------+
| Name | Versions | Commit Hash |
+-------------------+-----------------+-------------+
| cf | 236+dev.1* | 9a550e9d+ |
| diego | 0.1468.0+dev.1* | a54eeaf4+ |
| docker | 26* | 7fabb47c+ |
| etcd | 45* | 96dab618+ |
| garden-linux | 0.337.0* | a7d9ddac |
+-------------------+-----------------+-------------+

buildpack position enabled locked filename
staticfile_buildpack 1 true false staticfile_buildpack-cached-v1.3.6.zip
java_buildpack 2 true false java-buildpack-v3.7.zip
ruby_buildpack 3 true false ruby_buildpack-cached-v1.6.16.zip
nodejs_buildpack 4 true false nodejs_buildpack-cached-v1.5.12.zip
go_buildpack 5 true false go_buildpack-cached-v1.7.5.zip
python_buildpack 6 true false python_buildpack-cached-v1.5.5.zip
php_buildpack 7 true false php_buildpack-cached-v4.3.10.zip
binary_buildpack 8 true false binary_buildpack-cached-v1.0.1.zip
admin_console_buildpack 9 true false admin_console_buildpack-cached-v1.6.12.zip