Update src/main/java/org/apache/skywalking/banyandb/v1/client/MeasureWrite.java

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: wu-sheng

src/main/java/org/apache/skywalking/banyandb/v1/client/MeasureWrite.java

@@ -59,8 +59,7 @@ public MeasureWrite tag(String tagName, Serializable<BanyandbModel.TagValue> tag
      */
     @Override
     protected BanyandbMeasure.WriteRequest build(BanyandbCommon.Metadata metadata) {
-        if (!timestamp.isPresent() || timestamp.get() <= 0) {
-            throw new IllegalArgumentException("timestamp is invalid.");
+            throw new IllegalArgumentException("Timestamp is required and must be greater than 0 for measure writes.");
         }
         Timestamp ts = Timestamp.newBuilder()
                 .setSeconds(timestamp.get() / 1000)