DATAMONGO-1533 - Polishing.

Extend JavaDoc. Minor reformatting.

Original pull request: spring-projects#428.

Author: mp911de

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/AggregationSpELExpression.java

@@ -53,7 +53,7 @@ private AggregationSpELExpression(String rawExpression, Object[] parameters) {
 	/**
 	 * Creates new {@link AggregationSpELExpression} for the given {@literal expressionString} and {@literal parameters}.
 	 *
-	 * @param expression must not be {@literal null}.
+	 * @param expressionString must not be {@literal null}.
 	 * @param parameters can be empty.
 	 * @return
 	 */
@@ -63,6 +63,9 @@ public static AggregationSpELExpression expressionOf(String expressionString, Ob
 		return new AggregationSpELExpression(expressionString, parameters);
 	}
 
+	/* (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.aggregation.AggregationExpression#toDbObject(org.springframework.data.mongodb.core.aggregation.AggregationOperationContext)
+	 */
 	@Override
 	public Document toDocument(AggregationOperationContext context) {
 		return (Document) TRANSFORMER.transform(rawExpression, context, parameters);