Failed deployments leak application classloaders in JBoss SuspendController and UndertowContainerProvider

Issue

• We were try to deploy applications that had some recurring deployment errors. This then led to an OutOfMemoryError and the heap dump shows leaked application classloaders accumulating through references in the JBoss SuspendController:

Class Name                                                                                              | Ref. Objects | Shallow Heap | Ref. Shallow Heap | Retained Heap
--------------------------------------------------------------------------------------------------------------------------------------------------
value org.jboss.as.server.suspend.SuspendController @ 0x4c2130d20                                       |          550 |           48 |            48,400 |         3,496
'- activities java.util.ArrayList @ 0x4c2130d68                                                         |          550 |           24 |            48,400 |         3,336
   '- elementData java.lang.Object[823] @ 0x56eda0df8                                                   |          550 |        3,312 |            48,400 |         3,312
      |- [148] org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$2 @ 0x579164a68  |            1 |           24 |                88 |            24
      |  '- this$0 org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService @ 0x51276a370|            1 |          176 |                88 |         2,424
      |     '- module org.jboss.modules.Module @ 0x51276a728                                            |            1 |           56 |                88 |       208,704
      |        '- moduleClassLoader org.jboss.modules.ModuleClassLoader @ 0x575161fb0                   |            1 |           88 |                88 |     1,224,776

• And they are also accumulated in references from the UndertowContainerProvider:

Class Name                                                                  | Ref. Objects | Shallow Heap | Ref. Shallow Heap | Retained Heap
----------------------------------------------------------------------------------------------------------------------------------------------
[19] class io.undertow.websockets.jsr.UndertowContainerProvider @ 0xe2c84668|            5 |           24 |               480 |     2,121,200
'- webSocketContainers java.util.concurrent.ConcurrentHashMap @ 0xe2c85048  |            5 |           64 |               480 |     2,120,840
   '- table java.util.concurrent.ConcurrentHashMap$Node[16] @ 0xe2c85088    |            5 |           80 |               480 |     2,120,776
      |- [14] java.util.concurrent.ConcurrentHashMap$Node @ 0xe2c850d8      |            2 |           32 |               192 |       848,032
      |  |- key org.jboss.modules.ModuleClassLoader @ 0xe2ac72f0            |            1 |           96 |                96 |         3,848
      |  |- next java.util.concurrent.ConcurrentHashMap$Node @ 0xe1c45918   |            1 |           32 |                96 |       424,200
      |  |  '- key org.jboss.modules.ModuleClassLoader @ 0xe2dd4400         |            1 |           96 |                96 |         3,904