Update Tomcat ServerProperties to support the RemoteIpValve portHeader
property.

Fixes gh-1616

The `protocolHeader` and `remoteIpHeader` no longer have default values
and must be opt-in.

Fixes gh-1624

In some scenarios, the ErrorPageFilter will want to forward the request
to an error page but the response has already been committed. One common
cause of this is when the filter’s running on WAS. WAS calls
flushBuffer() (which commits the response), upon a clean exit from a
servlet’s service method.

Previously, the filter would attempt the forward, even if the response
was committed. This would result in an IllegalStateException and a
possibly incomplete response that may also have an incorrect status
code.

This commit updates the ErrorPageFilter to check to see if the response
has already been committed before it attempts to forward the request to
the error page. If the response has already been committed, the filter
logs an error and allows the container’s normal handling to kick in.
This prevents an IllegalStateException from being thrown.

This commit also updates the response wrapper to keep track of when
sendError has been called. Now, when flushBuffer is called, if
sendError has been called, the wrapper calls sendError on the wrapped
response. This prevents the wrapper from suppressing an error when the
response is committed before the request handling returns to the error
page filter.

Closes gh-1575

Remove accidental addition of a 1.2 test.

If the actuator endpoints are configured on a different port then there
are some settings in the main ServerProperties that we would like to
re-use (e.g. the access log). The easiest way to do that is to just
configure the management server using the same ServerProperties instance
and then overwrite the things that are different (and stored in
ManagementServerProperties).

Fixes gh-1581

If user creates a Thymeleaf app with a parent-child context then the
child should contain all the web-specific pieces (and they are likely
to fail fast if they need to be ServletContextAware, or slower if they
try to locate a WebApplicationContext at runtime). This can't happen
if the view resolver is being added to the parent.

Freemarker and Velocity already have similar tests because it is assumed
that they should be usable outside a web app, so this change just does the
same for Thymeleaf.

Fixes gh-1611

Fix links to `actuator-noweb`, `actuator-log4j` and `hornetq` samples.

Fixes gh-1613

Update RelaxedConversionService to also support String to char[]
conversion. Primarily to support the `password` field in
MongoProperties.

Fixes gh-1572

Update ConfigFileApplicationListener to include more debug level output.
Debug messages are recorded during onApplicationEnvironmentPreparedEvent
but not actually output until onApplicationPreparedEvent. This is
because the logging level might not have been correctly set until the
context is completely prepared.

Fixes gh-1584

Previously, only the state of the primary connector was checked when
verifying that the embedded Tomcat instance has started successfully.
This commit updates the verification logic to examine all of the
service's connectors, thereby also detecting startup failures of any
additional connectors the have been configured.

A check on the primary connector's state has been removed from
initialize as, at this stage, its state will always be NEW.

Fixes gh-1591

See gh-1599

Closes gh-1596

Some frameworks handle all requests in a Filter, so you have to
explicitly register it as an ERROR dispatcher.

See gh-1272

Done in order to align with the rest of the configuration. Absent this
check, the bean will be installed in non-web applications without the
corresponding dependencies, causing the bootstrap to fail.

Closes gh-1588

Corrected the documentation to refer to file as tests.groovy, rather
than test.groovy. Updated cope snippet as tests.groovy should expect
"Hello World!" rather than "Hello World".

Closes gh-1593

... or couldn't hurt anyway.

1. Extends the definition of a web application for @ConditionalOnWebapp
so that a StandardEnvironment can be used (cutting out JNDI failures
for Environment properties)

2. Doesn't bother using StandardServletEnvironment in integration tests

3. Make the NON_ENUMERABLE_ENUMERABLES in PropertySourcesPropertyValues
static so they only get initialized once (not a huge issue at all)

Use File.separator rather than hard-coding the use of ‘/‘

Closes gh-1571

Update `LogbackLoggingSystem` to call the `reset()` method on the
`LoggerContext` before initialization.

This will hopefully reset the context to prevent the same appenders
from being accidentally added more than once.

Fixes gh-1091

This is a continuation of the changes made in 611f9781. It makes some
more @Bean methods public and adds tests to spring-boot-actuator and
spring-boot-autoconfigure to prevent against non-public methods being
introduced in the future

Closes gh-1571

Fixes gh-1571

Fixes gh-1570
Cherry-picked from 0960908b and 258c6f11

Fixes gh-1548 again

Previously, EnableAutoConfigurationImportSelector assumed that it
would always find auto-configuration attributes from an
@EnableAutoConfiguration annotation. This assumption does not hold
true in certain circumstances, although exactly what those
circumstances are is unclear. It could occur if the import selector
were used directly, but it's package-private making that unlikey. In
such circumstances a NullPointerException was being thrown.

This commit asserts that the attributes are non-null and, should the
assertion fail, produces an error that is more helpful than an NPE.

Closes gh-1512

Closes gh-1522

Closes gh-1540

The fix for gh-1475 introduced the use of an artifact's group to
discriminate between two libraries with the same name (artifact id)
and version. However, in the case of Gradle, a group name was not
provided for libraries that have been resolved from a repository.

This commit updates ResolvedArtifactLibrary to use the group obtained
from the underlying ResolvedArtifact as its discriminator.

Fixes gh-1543

User can set those properties (optionally) to use a different
DataSource than the default.

Fixes gh-1558

When MVC path matchers are used as metric keys, they can still contain
invalid characters and patterns (like asterisks). This change removes
some more special characters and also tidies up the names a bit so
no key part starts or ends with "-" (which is ugly).

Fixes gh-1528

Protecting /error doesn't make a great deal of sense and if it is
protected you don't get the ErrorPageFilter for the attempt at loading
it, so Tomcat renders its own HTML error page (when deployed as WAR).

Fixes gh-1548

Fixes gh-1534