Release 2.6.0-alpha-4: update versions
diff --git a/gradle.properties b/gradle.properties
index 5a478a7..8079cc3 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -13,9 +13,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-groovyVersion = 2.6.0-SNAPSHOT
+groovyVersion = 2.6.0-alpha-4
 # bundle version format: major('.'minor('.'micro('.'qualifier)?)?)? (first 3 only digits)
-groovyBundleVersion = 2.6.0.SNAPSHOT
+groovyBundleVersion = 2.6.0-alpha-4
 
 gradle_version=4.8.1