86732509 updated the plugin so that the application plugin is no longer
applied by default. This exposed three problems:

 1. bootRepackage may run before findMainClass has run, leaving it with
    an unknown main class.
 2. findMainClass may run before the classes have been built, making it
    unable to find the main class by examining the class files
 3. The project's mainClassName property was still being used as a
    convention for the bootRun task's main property. If the application
    plugin has not be applied, then this property does not exist.

The first problem has been addressed by configuring bootRepackage to
depend on findMainClass.

The second problem has been addressed by configuring the main source
set's output as an input of findMainClass, and configuring findMainClass
to depend on the tasks that build the output.

The third problem has been addressed by only using the mainClassName
property if it exists and its value is not null. We then fallback to
using the mainClassName property on the project's extra properties in
the same way. 

See gh-2679

Previously, the Spring Boot Gradle plugin would always apply the
application plugin to a project. It then piggy-backed on the application
plugin’s mainClassName and applicationDefaultJvmArgs properties for the
configuration of the bootRun task.

This commit updates the Spring Boot Gradle plugin so that it no longer
applies the application plugin. If the user applies the application
plugin then its configuration will be used, but it’s a no longer
requirement.

Users who do not need the application plugin, but who were using the
mainClassName or applicationDefaultJvmArgs properties will need to
change their builds as a result of this change as those properties will
no longer exist. As before, the mainClassName can be configured on the
springBoot extension:

springBoot {
	mainClassName 'com.example.YourApplication'
}

The applicationDefaultJvmArgs property can be used, but it must now be
declared with the project's ext block. For example:

ext {
	applicationDefaultJvmArgs = [ '-Dcom.example.property=true' ]
}

Closes gh-2679

Typically, a Spring Boot maintenance release would not move to a new
minor version of a dependency. However there is a security
vulnerability in Groovy [1] and 2.4.4 is the only release which
contains a fix for it.

The commit upgrades to 2.4.4, thereby ensuring that users of Groovy
are not vulnerable by default. Users of Groovy whose applications are
not affected by the vulnerability may choose to downgrade back to
2.3.11 by overriding Spring Boot's dependency management.

Closes gh-3540

[1] http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-3253

With this change a user can have `@EnableOAuth2Client` without
`@EnableOAuth2Sso`.

Fixes gh-3568

* pr/3561:
  Polish docs

Closes gh-3561

Also copies the ExpressionParser (the only public getter), trust
resolver and permission evaluator (if available in the context). Changes
the logic to not replace an existing OAuth2MethodSecurityExpressionHandler
so that users can override simply by providing a bean of that type.

Fixes gh-3542

Various areas of the code expect the management's context path to not
contain any trailing slash but nothing is enforcing it. We now make sure
to remove any trailing slash, including the one for '/' and make that
explicit via the Javadoc of the getter.

Fixes gh-3553

Use canonical version for the management's context path.

Closes gh-3546, closes gh-3547

* pr/3545:
  Polish JsonParserFactory javadoc

Closes gh-3545

Restore the deprecated method to give people a change to migrate. The
@DeprecatedConfigurationProperties annotation is now used to generate
the deprecated meta-data, removing the need for manual meta-data.

Closes gh-3537

Add a new @DeprecatedConfigurationProperties annotation which can be
used by the `ConfigurationMetadataAnnotationProcessor` to generating
meta-data deprecated blocks.

Fixes gh-3543

Closes gh-3537

* pr/3531:
  Fix typos

Closes gh-3531

Add missing default value

Set `server.session.persistent=true` when running DevTools to ensure
persistent sessions are used.

Fixes gh-3530

Update Tomcat, Jetty and Undertow to serialize session data when the
application is stopped and load it again when the application restarts.

Persistent session are opt-in; either by setting `persistentSession`
on the ConfigurableEmbeddedServletContainer or by using the property
`server.session.persistent=true`.

Fixes gh-2490

Add ApplicationTemp class which can be used to obtain a temp folder
based on the running application. Allows restarted application to
find temp files saved in a previous run.

Fixes gh-3529

Closes gh-3052

See gh-3493

Closes gh-3493
Closes gh-3494

Previously, the prefix was spring.embedded-mongodb. This was
inconsistent with the prefixes for Artermis and HornetQ which are
spring.artemis.embedded and spring.hornetq.embedded respectively.

See gh-2002

Make sure that Boot's FATAL level is mapped to log4j and log4j2 properly.

Fixes gh-3518

Embedded MongoDB is now auto-configured when it is on the classpath.
The Mongo instance will listen on the port specified by the
spring.data.mongodb.port property. If this property has a value of
zero and randomly allocated port will be used. In such an event, the
MongoClient created by MongoAutoConfiguration will be automatically
configured to use the port that was allocated.

By default, MongoDB 2.6.10 will be used. This can be configured using
the spring.embedded-mongodb.version property. Mongo's sync delay
feature is enabled by default. This can be configured using the
spring.embedded-mongobd.features property.

Closes gh-2002