feat: improve json stream writer json to proto conversion speed by

caching the schema. This will introduce approximately 2x improvement to
append speed

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

@@ -259,6 +259,22 @@ public AppendSerializationError(
     }
   }
 
+  /**
+   * This exception is thrown from to proto converter to wrap the row index to error mapping.
+   */
+  static class RowIndexToErrorException extends IllegalArgumentException {
+    Map<Integer, String> rowIndexToErrorMessage;
+
+    public RowIndexToErrorException(
+        Map<Integer, String> rowIndexToErrorMessage) {
+      this.rowIndexToErrorMessage = rowIndexToErrorMessage;
+    }
+
+    public String getMessage() {
+      return "The map of row index to error message is " + rowIndexToErrorMessage.toString();
+    }
+  }
+
   /** This exception is used internally to handle field level parsing errors. */
   public static class FieldParseError extends IllegalArgumentException {
     private final String fieldName;