DATACMNS-1804 - Correct grammar in Exception messages thrown by Repository classes.

Original pull request: #467.

Author: jxblum

src/main/java/org/springframework/data/repository/core/support/RepositoryFactorySupport.java

@@ -81,6 +81,7 @@
  * @author Mark Paluch
  * @author Christoph Strobl
  * @author Jens Schauder
+ * @author John Blum
  */
 @Slf4j
 public abstract class RepositoryFactorySupport implements BeanClassLoaderAware, BeanFactoryAware {
@@ -477,7 +478,7 @@ private void validate(RepositoryInformation repositoryInformation, RepositoryCom
 			if (composition.isEmpty()) {
 
 				throw new IllegalArgumentException(
-						String.format("You have custom methods in %s but not provided a custom implementation!",
+						String.format("You have custom methods in %s but have not provided a custom implementation!",
 								repositoryInformation.getRepositoryInterface()));
 			}