[common] Boundary case of Write buffer that throw IndexOutOfBoundsExc…

fluss-common/src/main/java/com/alibaba/fluss/record/ChangeTypeVectorWriter.java

@@ -36,7 +36,7 @@ public ChangeTypeVectorWriter(MemorySegment segment, int startPosition) {
     }
 
     public void writeChangeType(ChangeType changeType) {
-        if (recordsCount > capacity) {
+        if (recordsCount >= capacity) {
             // TODO: support AbstractPagedOutputView to have extendable capacity
             throw new IllegalStateException("The change type vector is full.");
         }

fluss-common/src/test/java/com/alibaba/fluss/record/ChangeTypeVectorWriterTest.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright (c) 2025 Alibaba Group Holding Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.alibaba.fluss.record;
+
+import com.alibaba.fluss.memory.MemorySegment;
+
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+/** Tests for {@link ChangeTypeVectorWriter}. */
+public class ChangeTypeVectorWriterTest {
+
+    @Test
+    public void testReproduceOriginalIndexOutOfBoundsExceptionScenario() {
+        int segmentSize = 131072; // 128KB
+        MemorySegment segment = MemorySegment.allocateHeapMemory(segmentSize);
+
+        // Create a ChangeTypeVectorWriter that uses the entire segment
+        ChangeTypeVectorWriter writer = new ChangeTypeVectorWriter(segment, 0);
+
+        // Write records up to capacity
+        for (int i = 0; i < segmentSize; i++) {
+            writer.writeChangeType(ChangeType.INSERT);
+        }
+
+        // This should now throw IllegalStateException instead of IndexOutOfBoundsException
+        assertThatThrownBy(() -> writer.writeChangeType(ChangeType.INSERT))
+                .isInstanceOf(IllegalStateException.class)
+                .hasMessage("The change type vector is full.");
+    }
+}