[MINOR] fix compile error

Author: Zhao, Qingwen <qingwzhao@apache.org>

Closes #962 from qingwen220/minor.
diff --git a/eagle-core/eagle-metadata/eagle-metadata-base/src/main/java/org/apache/eagle/metadata/resource/PolicyResource.java b/eagle-core/eagle-metadata/eagle-metadata-base/src/main/java/org/apache/eagle/metadata/resource/PolicyResource.java
index 3b3dba9..13041cf 100644
--- a/eagle-core/eagle-metadata/eagle-metadata-base/src/main/java/org/apache/eagle/metadata/resource/PolicyResource.java
+++ b/eagle-core/eagle-metadata/eagle-metadata-base/src/main/java/org/apache/eagle/metadata/resource/PolicyResource.java
@@ -103,7 +103,7 @@
             policyEntity.setDefinition(policyDefinition);
 
             List<Publishment> alertPublishments = metadataResource.getPolicyPublishments(policyId);
-            if (alertPublishments != null && !alertPublishments.isEmpty()){
+            if (alertPublishments != null && !alertPublishments.isEmpty()) {
                 List<String> alertPublisherIds = new ArrayList<>();
                 for (Publishment publishment : alertPublishments) {
                     alertPublisherIds.add(publishment.getName());