Documentation fixes (#317)

* Polish + Fixed service-registry endpoint + Added features endpoint docs

Fixes #53 
Fixes #310

.github/CONTRIBUTING.md

@@ -9,15 +9,15 @@ follow the guidelines below.
 
 ## Sign the Contributor License Agreement
 Before we accept a non-trivial patch or pull request we will need you to sign the
-https://cla.pivotal.io/sign/spring[Contributor License Agreement].
+[Contributor License Agreement](https://cla.pivotal.io/sign/spring).
 Signing the contributor's agreement does not grant anyone commit rights to the main
 repository, but it does mean that we can accept your contributions, and you will get an
 author credit if we do.  Active contributors might be asked to join the core team, and
 given the ability to merge pull requests.
 
 ## Code of Conduct
-This project adheres to the Contributor Covenant https://github.com/spring-cloud/spring-cloud-build/blob/master/docs/src/main/asciidoc/code-of-conduct.adoc[code of
-conduct]. By participating, you  are expected to uphold this code. Please report
+This project adheres to the Contributor Covenant [code of
+conduct](https://github.com/spring-cloud/spring-cloud-build/blob/master/docs/src/main/asciidoc/code-of-conduct.adoc). By participating, you  are expected to uphold this code. Please report
 unacceptable behavior to spring-code-of-conduct@pivotal.io.
 
 ## Code Conventions and Housekeeping
@@ -27,10 +27,8 @@ added after the original pull request but before a merge.
 * Use the Spring Framework code format conventions. If you use Eclipse
   you can import formatter settings using the
   `eclipse-code-formatter.xml` file from the
-  https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/spring-cloud-dependencies-parent/eclipse-code-formatter.xml[Spring
-  Cloud Build] project. If using IntelliJ, you can use the
-  http://plugins.jetbrains.com/plugin/6546[Eclipse Code Formatter
-  Plugin] to import the same file.
+  [Spring Cloud Build](https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/spring-cloud-dependencies-parent/eclipse-code-formatter.xml) project. If using IntelliJ, you can use the
+  [Eclipse Code Formatter Plugin](http://plugins.jetbrains.com/plugin/6546) to import the same file.
 * Make sure all new `.java` files to have a simple Javadoc class comment with at least an
   `@author` tag identifying you, and preferably at least a paragraph on what the class is
   for.
@@ -42,6 +40,6 @@ added after the original pull request but before a merge.
 * A few unit tests would help a lot as well -- someone has to do it.
 * If no-one else is using your branch, please rebase it against the current master (or
   other target branch in the main project).
-* When writing a commit message please follow http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html[these conventions],
+* When writing a commit message please follow [these conventions](http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html),
   if you are fixing an existing issue please add `Fixes gh-XXXX` at the end of the commit
   message (where XXXX is the issue number).

docs/src/main/asciidoc/spring-cloud-commons.adoc

@@ -322,7 +322,7 @@ on the classpath to cause the Spring Boot application to register with the servi
 
 ==== Health Indicator
 
-Commons creates a Spring Boot `HealthIndicator` that `DiscoveryClient` implementations can participate in by implementing `DiscoveryHealthIndicator`. To disable the composite `HealthIndicator` set `spring.cloud.discovery.client.composite-indicator.enabled=false`. A generic `HealthIndicator` based on `DiscoveryClient` is auto-configured (`DiscoveryClientHealthIndicator). To disable it, set `spring.cloud.discovery.client.health-indicator.enabled=false`. To disable the description field of the `DiscoveryClientHealthIndicator` set `spring.cloud.discovery.client.health-indicator.include-description=false`, otherwise it can bubble up as the `description` of the rolled up `HealthIndicator`.
+Commons creates a Spring Boot `HealthIndicator` that `DiscoveryClient` implementations can participate in by implementing `DiscoveryHealthIndicator`. To disable the composite `HealthIndicator` set `spring.cloud.discovery.client.composite-indicator.enabled=false`. A generic `HealthIndicator` based on `DiscoveryClient` is auto-configured (`DiscoveryClientHealthIndicator`). To disable it, set `spring.cloud.discovery.client.health-indicator.enabled=false`. To disable the description field of the `DiscoveryClientHealthIndicator` set `spring.cloud.discovery.client.health-indicator.include-description=false`, otherwise it can bubble up as the `description` of the rolled up `HealthIndicator`.
 
 === ServiceRegistry
 
@@ -357,7 +357,7 @@ By default, the `ServiceRegistry` implementation will auto-register the running
 
 ==== Service Registry Actuator Endpoint
 
-A `/service-registry` actuator endpoint is provided by Commons. This endpoint relys on a `Registration` bean in the Spring Application Context. Calling `/service-registry/instance-status` via a GET will return the status of the `Registration`. A POST to the same endpoint with a `String` body will change the status of the current `Registration` to the new value. Please see the documentation of the `ServiceRegistry` implementation you are using for the allowed values for updating the status and the values retured for the status.
+A `/service-registry` actuator endpoint is provided by Commons. This endpoint relies on a `Registration` bean in the Spring Application Context. Calling `/service-registry` via a GET will return the status of the `Registration`. A POST to the same endpoint with a JSON body will change the status of the current `Registration` to the new value. The JSON body has to include the `status` field with the preferred value. Please see the documentation of the `ServiceRegistry` implementation you are using for the allowed values for updating the status and the values returned for the status. For instance, Eureka's supported statuses are `UP`, `DOWN`, `OUT_OF_SERVICE` and `UNKNOWN`.
 
 === Spring RestTemplate as a Load Balancer Client
 
@@ -617,3 +617,46 @@ the default factories will use these builders as the basis for the builders retu
 You can also disable the creation of these beans by setting
 `spring.cloud.httpclientfactories.apache.enabled` or `spring.cloud.httpclientfactories.ok.enabled` to
 `false`.
+
+[[enabled-features]]
+=== Enabled Features
+
+A `/features` actuator endpoint is provided by Commons. This endpoint returns features available on the classpath and if they are enabled or not. The information returned includes the feature type, name, version and vendor.
+
+==== Feature types
+
+There are two types of 'features': abstract and named.
+
+Abstract features are features where an interface or abstract class is defined that an implementation creates, such as `DiscoveryClient`, `LoadBalancerClient` or `LockService`. The abstract class or interface is used to find a bean of that type in the context. The version displayed is `bean.getClass().getPackage().getImplementationVersion()`.
+
+Named features are features that don't have a particular class they implement, such as "Circuit Breaker", "API Gateway", "Spring Cloud Bus", etc... These features require a name and a bean type.
+
+==== Declaring features
+
+Any module can declare any number of `HasFeature` beans. Some examples:
+
+[source,java,indent=0]
+----
+@Bean
+public HasFeatures commonsFeatures() {
+  return HasFeatures.abstractFeatures(DiscoveryClient.class, LoadBalancerClient.class);
+}
+
+@Bean
+public HasFeatures consulFeatures() {
+  return HasFeatures.namedFeatures(
+    new NamedFeature("Spring Cloud Bus", ConsulBusAutoConfiguration.class),
+    new NamedFeature("Circuit Breaker", HystrixCommandAspect.class));
+}
+
+@Bean
+HasFeatures localFeatures() {
+  return HasFeatures.builder()
+      .abstractFeature(Foo.class)
+      .namedFeature(new NamedFeature("Bar Feature", Bar.class))
+      .abstractFeature(Baz.class)
+      .build();
+}
+----
+
+Each of these beans should go in an appropriately guarded `@Configuration`.