EuiComboBox inputRef not accessible

[ekline-expnet]

The documentation shows the property inputRef is available on EuiComboBox.
I thought I was using it to set focus, but after updating EUI, the code stopped working.

Looking at combo_box.tsx, the inputRef is pulled out of the props on line 889, but then the inputRef is set on line 1034 to be inputRef={this.searchInputRefCallback} and the props.inputRef is never called if present.

[chandlerprall]

Looks like a regression caused by #2838 which omitted the call to the provided inputRef.