Remove ReturnListener in RpcClient#close()

[JHahnHRO]

Proposed Changes

Remove the ReturnListener in RpcClient#close() that is added in the constructor.

Types of Changes

• Bugfix (non-breaking change which fixes issue Memory leak in RpcClient #1168)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation (correction or otherwise)
• Cosmetics (whitespace, appearance)

Checklist

• I have read the CONTRIBUTING.md document
• I have signed the CA (see https://cla.pivotal.io/sign/rabbitmq)
• All tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)
• Any dependent changes have been merged and published in related repositories

Further Comments

None.

[pivotal-cla]

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[JHahnHRO]

@pivotal-cla This is an Obvious Fix

[pivotal-cla]

@JHahnHRO This Pull Request contains an obvious fix. Signing the Contributor License Agreement is not necessary.

[michaelklishin]

Backported to 5.x. Thank you, @JHahnHRO.