Extract duplicate snippets as document anchors.

See gh-25912

See gh-25912

Closes gh-25918

Closes gh-25917

See gh-25912

See gh-25908

See gh-25908

This commit extends the fix from b86c11cc
by checking for both existing Content-Length and Transfer-Encoding.

Closes gh-25908

Prior to this commit only Propagation.NOT_SUPPORTED was supported for
disabling test-managed transactions via the `propagation` attribute of
`@Transactional`.

This commit allows users to specify Propagation.NOT_SUPPORTED or
Propagation.NEVER to disable test-managed transactions.

Closes gh-25909

Those tests produce intermittent build errors.

This commit raises the minimum Coroutines version supported
to 1.4.0-M1 and above, and changes usages of awaitFirst() or
awaitFirstOrNull() to awaitSingle() or awaitSingleOrNull()
to fix gh-25007.

Closes gh-25914
Closes gh-25007

# Conflicts:
#	spring-web/src/test/java/org/springframework/http/converter/json/Jackson2ObjectMapperBuilderTests.java
#	spring-web/src/test/java/org/springframework/http/converter/json/Jackson2ObjectMapperFactoryBeanTests.java

See gh-25907

Closes gh-25907

See gh-19930

See gh-19930

# Conflicts:
#	build.gradle

# Conflicts:
#	spring-webflux/src/main/java/org/springframework/web/reactive/result/method/InvocableHandlerMethod.java

Closes gh-25901

Prior to this commit, the EnclosingConfiguration mode used in
conjunction with @NestedTestConfiguration defaulted to INHERIT.

In other to allow development teams to change the default to OVERRIDE
(e.g., for compatibility with Spring Framework 5.0 through 5.2), this
commit introduces support for changing the default EnclosingConfiguration
mode globally via a JVM system property or via the SpringProperties
mechanism.

For example, the default may be changed to
EnclosingConfiguration.OVERRIDE by supplying the following JVM system
property via the command line.

-Dspring.test.enclosing.configuration=override

Closes gh-19930

Closes gh-25900

See gh-25898

See gh-19930

Closes gh-25829