#1172, for proxy

[tuohai666]

Fixes #1172.

[coveralls]

Pull Request Test Coverage Report for Build 5111

• 0 of 23 (0.0%) changed or added relevant lines in 3 files are covered.
• 2 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.1%) to 63.466%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
sharding-proxy/src/main/java/io/shardingsphere/proxy/Bootstrap.java	0	1	0.0%
sharding-proxy/src/main/java/io/shardingsphere/proxy/frontend/mysql/MySQLFrontendHandler.java	0	4	0.0%
sharding-proxy/src/main/java/io/shardingsphere/proxy/backend/jdbc/connection/BackendConnection.java	0	18	0.0%

Files with Coverage Reduction	New Missed Lines	%
sharding-proxy/src/main/java/io/shardingsphere/proxy/backend/jdbc/connection/BackendConnection.java	1	0.0%
sharding-proxy/src/main/java/io/shardingsphere/proxy/frontend/mysql/MySQLFrontendHandler.java	1	0.0%

Totals
Change from base Build 5108:	-0.1%
Covered Lines:	8057
Relevant Lines:	12695

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💛 - Coveralls