DATAMONGO-1761 - Polishing.

Refactor MongoConverter.mapValueToTargetType to imperative method instead of returning a function for easier consumption. Adapt return types in Javadoc to the actual return type. Remove undocumented type parameters. Add overload using reified entity and return type generics. Slight documentation tweaks.

Original pull request: #494.
Related pull request: #514.

src/main/asciidoc/new-features.adoc

@@ -4,6 +4,7 @@
 [[new-features.2-1-0]]
 == What's new in Spring Data MongoDB 2.1
 * Cursor-based aggregation execution.
+* <<mongo-template.query.distinct,Distinct queries>> for imperative and reactive Template API.
 
 [[new-features.2-0-0]]
 == What's new in Spring Data MongoDB 2.0

src/main/asciidoc/reference/mongodb.adoc

@@ -1090,8 +1090,9 @@ The query methods need to specify the target type T that will be returned and th
 [[mongo-template.query.distinct]]
 === Query distinct values
 
-MongoDB allows obtaining distinct field values for a single field. The stored values do not have to have the same data type to be considered, nor is the feature limited to simple types.
-However when retrieving distinct values the actual result type does matter for the sake of conversion.
+MongoDB provides an operation to obtain distinct values for a single field using a query from the resulting documents.
+Resulting values are not required to have the same data type, nor is the feature limited to simple types.
+For retriaval the actual result type does matter for the sake of conversion and typing.
 
 .Retrieving distinct values
 ====
@@ -1100,13 +1101,13 @@ However when retrieving distinct values the actual result type does matter for t
 template.query(Person.class)  <1>
   .distinct("lastname")       <2>
   .all();                     <3>
----
+----
 <1> Query the collection of `Person`.
 <2> Select _distinct_  values of the `lastname` field. The fieldname will be mapped according to the domain types property declaration, taking potential `@Field` annotations into account.
 <3> Retrieve all distinct values as `List` of `Object` due to no explicit result type specification.
 ====
 
-Retrieving distinct values into a `Collection` of `Object.class` is the most flexible way as it will try to determine the property value of the domain type converting results to the desired type or mapping `Document` structures.
+Retrieving distinct values into a `Collection` of `Object` is the most flexible way as it will try to determine the property value of the domain type converting results to the desired type or mapping `Document` structures.
 
 Sometimes, when all values of the desired field are fixed to a certain type, it is more convenient to directly obtain a correctly typed `Collection`
 
@@ -1118,12 +1119,12 @@ template.query(Person.class)  <1>
   .distinct("lastname")       <2>
   .as(String.class)           <3>
   .all();                     <4>
----
+----
 <1> Query the collection of `Person`.
 <2> Select _distinct_  values of the `lastname` field. The fieldname will be mapped according to the domain types property declaration, taking potential `@Field` annotations into account.
 <3> Retrieved values will be converted into the desired target type. In this case `String`. It would also be possible to map the values to a more complex type if the stored field contains a document.
 <4> Retrieve all distinct values as a `List` of `String`. Throws a `DataAccessException` if the type cannot be converted into the desired target type.
-===
+====
 
 [[mongo.geospatial]]
 === GeoSpatial Queries