DATAMONGO-2477 - Disable auto index creation by default.

Original pull request: #845.

src/main/asciidoc/reference/mapping.adoc

@@ -392,7 +392,7 @@ Automatic index creation is only done for types annotated with `@Document`.
 
 [NOTE]
 ====
-To turn automatic index creation _OFF_ please override `autoIndexCreation()` in your configuration.
+To turn automatic index creation _ON_ please override `autoIndexCreation()` in your configuration.
 [source,java]
 ----
 @Configuration
@@ -400,7 +400,7 @@ public class Config extends AbstractMongoClientConfiguration {
 
   @Override
   public boolean autoIndexCreation() {
-    return false;
+    return true;
   }
 
   // ...
@@ -408,7 +408,7 @@ public class Config extends AbstractMongoClientConfiguration {
 ----
 ====
 
-IMPORTANT: Automatic index creation will be turned _OFF_ by default with the release of 3.x.
+IMPORTANT: Automatic index creation is turned _OFF_ by default as of the release of 3.x.
 We recommend index creation to happen either out of band or as part of the application startup using
 `IndexOperations`.
 

src/main/asciidoc/upgrading.adoc

@@ -148,6 +148,52 @@ Element | Comment
 
 == Other Changes
 
+=== Auto Index Creation
+
+Annotation based index creation is now turned **OFF** by default and needs to be enabled eg. when relying on `@GeoSpatialIndexed`.
+
+.Enable Auto Index Creation
+====
+
+.XML Namespace
+[source,xml]
+----
+<mongo:mapping-converter auto-index-creation="true" /> <1>
+----
+
+.Java Config
+[source,java]
+----
+@Configuration
+public class Config extends AbstractMongoClientConfiguration {
+
+	@Override
+    protected boolean autoIndexCreation() { <2>
+        return true;
+    }
+
+    // ...
+}
+----
+
+.Programmatic
+[source,java]
+----
+MongoDatabaseFactory dbFactory = new SimpleMongoClientDatabaseFactory(...);
+DefaultDbRefResolver dbRefResolver = new DefaultDbRefResolver(dbFactory);
+
+MongoMappingContext mappingContext = new MongoMappingContext();
+mappingContext.setAutoIndexCreation(true); <3>
+// ...
+mappingContext.afterPropertiesSet();
+
+MongoTemplate template = new MongoTemplate(dbFactory, new MappingMongoConverter(dbRefResolver, mappingContext));
+----
+<1> Use the XML namespace attribute `auto-index-creation` on `mapping-converter`.
+<2> Overrride `autoIndexCreation` via `AbstractMongoClientConfiguration` or `AbstractReactiveMongoClientConfiguration`.
+<3> Set the flag on `MongoMappingContext`.
+====
+
 === UUID Types
 
 The MongoDB UUID representation can now be configured with different formats.
@@ -157,8 +203,8 @@ This has to be done via `MongoClientSettings` as shown in the snippet below.
 ====
 [source,java]
 ----
-
-static class Config extends AbstractMongoClientConfiguration {
+@Configuration
+public class Config extends AbstractMongoClientConfiguration {
 
     @Override
     public void configureClientSettings(MongoClientSettings.Builder builder) {