DATAJPA-1484 - Add build profile for Hibernate 6.

Added build profile Hibernate 6 snapshots. Introduced property for Hibernate group identifier as it's gonna change to org.hibernate.orm in 6.0.
Added the build profile to the Travis builds. Added explicit cast to the Hibernate implementation in PersistenceProvider as ScrollableResults now uses a generic type as return value for its ….get() method.

.travis.yml

@@ -13,6 +13,7 @@ env:
     - PROFILE=hibernate-53-next
     - PROFILE=hibernate-54
     - PROFILE=hibernate-54-next
+    - PROFILE=hibernate-6
     - PROFILE=eclipselink-next
     - PROFILE=eclipselink-27
     - PROFILE=eclipselink-27-next

pom.xml

@@ -23,6 +23,7 @@
 
 		<eclipselink>2.6.5</eclipselink>
 		<hibernate>5.2.17.Final</hibernate>
+		<hibernate.groupId>org.hibernate</hibernate.groupId>
 		<jpa>2.0.0</jpa>
 		<springdata.commons>2.0.13.BUILD-SNAPSHOT</springdata.commons>
 
@@ -81,6 +82,19 @@
 				</repository>
 			</repositories>
 		</profile>
+		<profile>
+			<id>hibernate-6-next</id>
+			<properties>
+				<hibernate>6.0.0-SNAPSHOT</hibernate>
+				<hibernate.groupId>org.hibernate.orm</hibernate.groupId>
+			</properties>
+			<repositories>
+				<repository>
+					<id>jboss</id>
+					<url>https://repository.jboss.org/nexus/content/repositories/public</url>
+				</repository>
+			</repositories>
+		</profile>
 		<profile>
 			<id>eclipselink-next</id>
 			<properties>
@@ -225,14 +239,14 @@
 		</dependency>
 
 		<dependency>
-			<groupId>org.hibernate</groupId>
+			<groupId>${hibernate.groupId}</groupId>
 			<artifactId>hibernate-core</artifactId>
 			<version>${hibernate}</version>
 			<optional>true</optional>
 		</dependency>
 
 		<dependency>
-			<groupId>org.hibernate</groupId>
+			<groupId>${hibernate.groupId}</groupId>
 			<artifactId>hibernate-jpamodelgen</artifactId>
 			<version>${hibernate}</version>
 			<scope>provided</scope>

src/main/java/org/springframework/data/jpa/provider/PersistenceProvider.java

@@ -380,7 +380,8 @@ public enum PersistenceProvider implements QueryExtractor, ProxyIdAccessor {
 				throw new NoSuchElementException("No ScrollableResults");
 			}
 
-			Object[] row = scrollableResults.get();
+			// Cast needed for Hibernate 6 compatibility
+			Object[] row = (Object[]) scrollableResults.get();
 
 			return row.length == 1 ? row[0] : row;
 		}