* pr/4709:
  Polish contribution
  Polish docs

Use the same value as we do.

Closes gh-4709

* pr/4701:
  Remove double instantiation of Manifest

Closes gh-4701

* pr/4685:
  Fix possible null pointer dereference

Closes gh-4685

* pr/4677:
  Polish

Closes gh-4677

Closes gh-4687

Previously, each 5xx response to a request that used a path variable
would result in a metric being recorded that contained the path
variable. Therefore, if a different path variable was included in each
request, a new metric would be recorded for each request. This is
problematic as it can lead to the metrics being flooded with unwanted
entries.

This commit updates MetricsFilter to treat 5xx responses sent before
mapping has occurred in the same way as 4xx and redirect responses.
A single metric, counter.status.500.unmapped, is now used.

Closes gh-4377

See gh-4679

Previously, ServerThread would check for a disconnect as soon as it
had been started. This raced with it handling its first connection. If
the check for disconnect won the race it would incorrectly determine
that the disconnect timeout had been reached and wouldn’t respond to
the connection.

This commit updates ServerThread so that it only checks the disconnect
timeout once it’s handled at least one connection.

Closes gh-4668

Closes gh-4630

Previously, the auto-configuration for embedded Mongo did not specify
a bind IP so Mongo was started without one. This would lead to Mongo
binding to all available network interfaces. This caused some friction
with the Windows firewall as it would ask for permission every time
embedded Mongo was launched.

This commit updates the auto-configuration to use
spring.data.mongodb.host to configure the bind IP for embedded Mongo.
If spring.data.mongodb.host is null, the auto-configuration will use
the loopback address instead.

Closes gh-4630

Closes gh-4502
Closes gh-4536

Closes gh-4639

Closes gh-4673

Closes gh-4679

Previously, disabling SecurityAutoConfiguration could cause
SecurityFilterAutoConfiguration to fail if Spring Security’s filter
chain bean existing in the context. SecurityFilterAutoConfiguration
relies on SecurityProperties which is created by
SecurityAutoConfiguration. When SecurityAutoConfiguration is disabled,
there’s no SecurityProperties bean so SecurityFilterAutoConfiguration
would fail due to the missing dependency.

This commit updates SecurityFilterAutoConfiguration to create a
SecurityProperties bean if one does not already exist.

Closes gh-4525

Closes gh-4327

Previously, when a session attribute that had been stored in Redis was
being deserialized, the app class loader would be used. This would
result in a ClassCastException if the attribute was an instance of a
class visible to the restart class loader.

This commit auto-configures Spring Session’s RedisTemplate to use a
custom deserializer that uses the restart class loader when
deserializing session attributes.

Closes gh-3805

Closes gh-4538

Previously, LoggingApplicationListener would clean up the logging
system in response to any application context with which it was
registered being closed. This caused problems when a child context was
closed. Specifically, closing the child context would cause any
SLF4J-based logging systems to unregister the JUL bridge handler
preventing an JUL logging being bridged into Logback or Log4J2.

This commit updates LoggingApplicationListener so that the logging
system is only cleaned up when a root application context is
closed.

Closes gh-4651

Previously, the test that verified that Undertow's access log could be
enabled and was written to the correct file expected the log to be
available as soon as the request to the server had completed. Undertow
writes the access log asynchronously so the test failed intermittently
due to a race between the access log being written and the test
asserting that it exists.

This commit updates the test to wait for up to 10 seconds for the
access log to be available.

See gh-4670

See gh-4670

Undertow 1.3.2 changed the default access log file suffix from '.log'
to just 'log'. Thus we need to adapt the file name pattern to include
the missing dot.

Closes gh-4670

Closes gh-4577

Closes gh-4548

Closes gh-4606

Previously, ServerThread.lastHttpRequestTime was written while
synchronized on this.httpConnections but was read without
synchronization. This could lead to a read of the field producing the
wrong value and cause premature connection timeout.

This commit moves the call to checkNotDisconnected into a block that
sychronizes on this.httpConnections, thereby ensuring that
lastHttpRequestTime can be read safely.

Closes gh-4668

Some libraries like aspectj are using findResource to see the raw
bytecode of a class. It will even call findResource for every method of
every class of beans that are post processed. This can be significant
performance hit on startup when LaunchedURLClassLoader and there are a
lot of nested jars.

See gh-3640
Fixes gh-4557