tests: Remove unnecessary null check for protobuf lists (#2723)

ErrorProne will complain ImpossibleNullComparison once protobuf runtime is upgraded to 4.x. See the downstream tests in sdk-platform-java.

Author: blakeli0

google-cloud-bigtable/src/test/java/com/google/cloud/bigtable/data/v2/stub/changestream/ReadChangeStreamMergingAcceptanceTest.java

@@ -285,20 +285,20 @@ public void test() throws Exception {
 
   private static boolean expectsError(ReadChangeStreamTest testCase) {
     List<ReadChangeStreamTest.Result> results = testCase.getResultsList();
-    return results != null && !results.isEmpty() && results.get(results.size() - 1).getError();
+    return !results.isEmpty() && results.get(results.size() - 1).getError();
   }
 
   private static List<ReadChangeStreamTest.Result> getNonExceptionResults(
       ReadChangeStreamTest testCase) {
     List<ReadChangeStreamTest.Result> results = testCase.getResultsList();
     List<ReadChangeStreamTest.Result> response = new ArrayList<>();
-    if (results != null) {
-      for (ReadChangeStreamTest.Result result : results) {
-        if (!result.getError()) {
-          response.add(result);
-        }
+
+    for (ReadChangeStreamTest.Result result : results) {
+      if (!result.getError()) {
+        response.add(result);
       }
     }
+
     return response;
   }
 }

google-cloud-bigtable/src/test/java/com/google/cloud/bigtable/data/v2/stub/readrows/ReadRowsMergingAcceptanceTest.java

@@ -142,20 +142,20 @@ public void test() throws Exception {
 
   private static boolean expectsError(ReadRowsTest rrt) {
     List<ReadRowsTest.Result> results = rrt.getResultsList();
-    return results != null && !results.isEmpty() && results.get(results.size() - 1).getError();
+    return !results.isEmpty() && results.get(results.size() - 1).getError();
   }
 
   private static List<ReadRowsTest.Result> getNonExceptionResults(ReadRowsTest rrt) {
     List<ReadRowsTest.Result> results = rrt.getResultsList();
 
     List<ReadRowsTest.Result> response = new ArrayList<>();
-    if (results != null) {
-      for (ReadRowsTest.Result result : results) {
-        if (!result.getError()) {
-          response.add(result);
-        }
+
+    for (ReadRowsTest.Result result : results) {
+      if (!result.getError()) {
+        response.add(result);
       }
     }
+
     return response;
   }
 }