ATLAS-1322: fix dereference null return value

webapp/src/main/java/org/apache/atlas/util/RestUtils.java

@@ -320,6 +320,7 @@ public final class RestUtils {
                                         if (isForeignKey) {
                                             AtlasType attribType = entityType.getAttributeType(attrDef.getName());
 
+                                            if (attribType != null) {
                                                 if (attribType.getTypeCategory() == TypeCategory.ARRAY) {
                                                     attribType = ((AtlasArrayType) attribType).getElementType();
                                                 }
@@ -328,12 +329,13 @@ public final class RestUtils {
                                                     String revAttrName = ((AtlasEntityType) attribType).
                                                             getMappedFromRefAttribute(entityType.getTypeName(), attrDef.getName());
 
-                                                if (StringUtils.equals(classTypeDefName , attrDef.getTypeName()) &&
+                                                    if (StringUtils.equals(classTypeDefName, attrDef.getTypeName()) &&
                                                             StringUtils.equals(oldAttr.name, revAttrName)) {
                                                         refAttrName = attrDef.getName();
                                                     }
                                                 }
                                             }
+                                        }
 
                                     }
                                 }