fix: allow repeated field to have a null or missing json array (#1760)

* feat: Throw explicit exception in the case of Json input has more fields than table schema of the table

* .

* fix: allow repeated field to have a null or missing json array

* .

* 🦉 Updates from OwlBot post-processor

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Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

Author: yirutang

google-cloud-bigquerystorage/src/main/java/com/google/cloud/bigquery/storage/v1/JsonToProtoMessage.java

@@ -502,6 +502,11 @@ private static void fillRepeatedField(
     try {
       jsonArray = json.getJSONArray(exactJsonKeyName);
     } catch (JSONException e) {
+      java.lang.Object val = json.get(exactJsonKeyName);
+      // It is OK for repeated field to be null.
+      if (val == JSONObject.NULL) {
+        return;
+      }
       throw new IllegalArgumentException(
           "JSONObject does not have a array field at " + currentScope + ".");
     }

google-cloud-bigquerystorage/src/test/java/com/google/cloud/bigquery/storage/v1/JsonToProtoMessageTest.java

@@ -1275,4 +1275,40 @@ public void testBadJsonFieldIntRepeated() throws Exception {
       assertEquals(ex.getMessage(), "Text 'blah' could not be parsed at index 0");
     }
   }
+
+  @Test
+  public void testNullRepeatedField() throws Exception {
+    TableSchema ts =
+        TableSchema.newBuilder()
+            .addFields(
+                0,
+                TableFieldSchema.newBuilder()
+                    .setName("test_repeated")
+                    .setType(TableFieldSchema.Type.DATE)
+                    .setMode(TableFieldSchema.Mode.REPEATED)
+                    .build())
+            .addFields(
+                1,
+                TableFieldSchema.newBuilder()
+                    .setName("test_non_repeated")
+                    .setType(TableFieldSchema.Type.DATE)
+                    .setMode(TableFieldSchema.Mode.NULLABLE)
+                    .build())
+            .build();
+    JSONObject json = new JSONObject();
+    // Null repeated field.
+    json.put("test_repeated", JSONObject.NULL);
+
+    DynamicMessage protoMsg =
+        JsonToProtoMessage.convertJsonToProtoMessage(RepeatedInt32.getDescriptor(), ts, json);
+    assertTrue(protoMsg.getAllFields().isEmpty());
+
+    // Missing repeated field.
+    json = new JSONObject();
+    json.put("test_non_repeated", JSONObject.NULL);
+
+    protoMsg =
+        JsonToProtoMessage.convertJsonToProtoMessage(RepeatedInt32.getDescriptor(), ts, json);
+    assertTrue(protoMsg.getAllFields().isEmpty());
+  }
 }

google-cloud-bigquerystorage/src/test/proto/jsonTest.proto

@@ -89,6 +89,7 @@ message RepeatedInt64 {
 
 message RepeatedInt32 {
   repeated int32 test_repeated = 1;
+  optional int32 test_non_repeated = 2;
 }
 
 message RepeatedDouble {