RequestHeader constructor to initialize trace-indicator as a string instead of integer

[IswaryaaS]

In ApplicationPattern package, onf-core-model-ap/applicationPattern/rest/client/RequestHeader , the class has a constructor that initializes a new trace-indicator if the incoming request does not have one.
Currently, this is being initialized as a integer.

Proposal:
The trace-indicator shall be initialized as string like below code snippet.

this.traceIndicator = traceIndicator;
        if (traceIndicator == undefined || traceIndicator.length == 0) {
            this.traceIndicator = ‘1’;
        }. 

[PrathibaJee]

Issue merged to branch v2.1.1_impl as a part of the PR #967.
Hence closing this issue.