HashMap throw a ConcurrentModificationException

[TonsnakeLin]

Bug Report

1. Describe the bug

When use rawkv-migration-tool to import data for TiKV, it threw ConcurrentModificationException

HashMap throws ConcurrentModificationException in certain scene, such as this

2. Minimal reproduce step (Required)

3. What did you see instead (Required)

4. What did you expect to see? (Required)

5. What is your Java Client and TiKV version? (Required)

3.1.11

• Client Java:
• TiKV: