feat: add clear_custom_fee_limits() to TopicMessageSubmitTransaction (#2483)

Signed-off-by: iron-prog <dt915725@gmail.com>

Author: iron-prog

src/hiero_sdk_python/consensus/topic_message_submit_transaction.py

@@ -162,6 +162,17 @@ def add_custom_fee_limit(self, custom_fee_limit: CustomFeeLimit) -> TopicMessage
         self.custom_fee_limits.append(custom_fee_limit)
         return self
 
+    def clear_custom_fee_limits(self) -> TopicMessageSubmitTransaction:
+        """
+        Clears all previously configured custom fee limits for the message submission.
+
+        Returns:
+            TopicMessageSubmitTransaction: This transaction instance (for chaining).
+        """
+        self._require_not_frozen()
+        self.custom_fee_limits = []
+        return self
+
     def _build_proto_body(self) -> consensus_submit_message_pb2.ConsensusSubmitMessageTransactionBody:
         """
         Returns the protobuf body for the topic message submit transaction.

tests/unit/topic_message_submit_transaction_test.py

@@ -99,6 +99,11 @@ def test_constructor_and_setters(topic_id, message, custom_fee_limit):
     assert tx_default.custom_fee_limits[0] == custom_fee_limit
     assert result is tx_default
 
+    # Test clear_custom_fee_limits
+    result = tx_default.clear_custom_fee_limits()
+    assert tx_default.custom_fee_limits == []
+    assert result is tx_default
+
 
 def test_set_methods_require_not_frozen(mock_client, topic_id, message, custom_fee_limit):
     """Test that setter methods raise exception when transaction is frozen."""
@@ -122,6 +127,16 @@ def test_set_methods_require_not_frozen(mock_client, topic_id, message, custom_f
             getattr(tx, method_name)(value)
 
 
+def test_clear_custom_fee_limits_requires_not_frozen(mock_client, topic_id, message, custom_fee_limit):
+    """Test that clear_custom_fee_limits() raises when the transaction is frozen."""
+    tx = TopicMessageSubmitTransaction(topic_id=topic_id, message=message)
+    tx.add_custom_fee_limit(custom_fee_limit)
+    tx.freeze_with(mock_client)
+
+    with pytest.raises(Exception, match="Transaction is immutable; it has been frozen"):
+        tx.clear_custom_fee_limits()
+
+
 def test_method_chaining(topic_id, message, custom_fee_limit):
     """Test method chaining functionality."""
     tx = TopicMessageSubmitTransaction()
@@ -144,6 +159,10 @@ def test_method_chaining(topic_id, message, custom_fee_limit):
     assert tx.chunk_size == chunk_size
     assert tx.max_chunks == max_chunks
 
+    result = tx.clear_custom_fee_limits()
+    assert result is tx
+    assert tx.custom_fee_limits == []
+
 
 def test_get_method():
     """Test retrieving the gRPC method for the transaction."""