DATAJPA-1622 - Polishing.

Added documentation and replaced lambdas with method references. Original pull request: spring-projects#397.

Author: schauder

src/main/java/org/springframework/data/jpa/domain/Specification.java

@@ -43,9 +43,9 @@ public interface Specification<T> extends Serializable {
 /**
  * Negates the given {@link Specification}.
  *
- * @param <T>
+ * @param <T> the type of the {@link Root} the resulting {@literal Specification} operates on.
  * @param spec can be {@literal null}.
- * @return
+ * @return guaranteed to be not {@literal null}.
  * @since 2.0
  */
 static <T> Specification<T> not(@Nullable Specification<T> spec) {
@@ -58,9 +58,9 @@ static <T> Specification<T> not(@Nullable Specification<T> spec) {
 /**
  * Simple static factory method to add some syntactic sugar around a {@link Specification}.
  *
- * @param <T>
+ * @param <T> the type of the {@link Root} the resulting {@literal Specification} operates on.
  * @param spec can be {@literal null}.
- * @return
+ * @return guaranteed to be not {@literal null}.
  * @since 2.0
  */
 static <T> Specification<T> where(@Nullable Specification<T> spec) {
@@ -76,7 +76,7 @@ static <T> Specification<T> where(@Nullable Specification<T> spec) {
  */
 
 default Specification<T> and(@Nullable Specification<T> other) {
-return composed(this, other, (builder, left, rhs) -> builder.and(left, rhs));
+return composed(this, other, CriteriaBuilder::and);
 }
 
 /**
@@ -87,7 +87,7 @@ default Specification<T> and(@Nullable Specification<T> other) {
  * @since 2.0
  */
 default Specification<T> or(@Nullable Specification<T> other) {
-return composed(this, other, (builder, left, rhs) -> builder.or(left, rhs));
+return composed(this, other, CriteriaBuilder::or);
 }
 
 /**