DATAMONGO-1533 - Polishing.

Enhance JavaDoc. Minor reformatting.

Original pull request: #428.

Author: mp911de

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

@@ -15,9 +15,10 @@
  */
 package org.springframework.data.mongodb.core.aggregation;
 
-import com.mongodb.DBObject;
 import org.springframework.util.Assert;
 
+import com.mongodb.DBObject;
+
 /**
  * An {@link AggregationExpression} that renders a MongoDB Aggregation Framework expression from the AST of a
  * <a href="http://docs.spring.io/spring/docs/current/spring-framework-reference/html/expressions.html">SpEL
@@ -53,7 +54,7 @@ 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 +64,9 @@ 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 DBObject toDbObject(AggregationOperationContext context) {
 		return (DBObject) TRANSFORMER.transform(rawExpression, context, parameters);