the issue of verifying contract file is not correct

Configured in \servicecomb-java-chassis\samples\bmi project:
<configuration>
<outputDir>./contracts</outputDir>
<sourceContractsDir>./sourceContracts</sourceContractsDir>
</configuration>

and modify one letter in contract file in ./contracts directory.

Command: mvn toolkit:verifyContracts

Result with something wrong:the result show that the contract file is the same.