Investigate null response on httpclient5

[meiao]

Description

In some cases, after an async request is made using httpclient5, the call is completed and a null Object is passed as the response.

This causes an NPE when the instrumentation is trying to get the http response code. Further, this prevents a segment from being finished, causing the transaction to appear to have taken 10 minutes (due to segment timeout).

Acceptance Criteria

Code is guarded to prevent NPE when the response is being read at

newrelic-java-agent/instrumentation/httpclient-5.0/src/main/java/com/nr/agent/instrumentation/httpclient50/InstrumentationUtils.java

Line 80 in 9f144fd

.status(response.getCode(), response.getReasonPhrase())

Also, end the segment in a finally block.

[workato-integration]

https://new-relic.atlassian.net/browse/NR-187310

[kford-newrelic]

Additional reference - NR-214951

[jbedell-newrelic]

Resolved by: #1719