Context macros are not expanded properly when no value defined

Steps to reproduce:

• Create item, external check with key, similar to this

  script.sh[http://localhost/{$TEST_PATH:"hello"}]
  

  

• create script.sh and put it to externalscripts folder:

  #!/bin/bash
  echo $1
  

Do not define {$TEST_PATH} or {$TEST_PATH:"hello"} macros at all.

Result:
Value in latest value:

http://localhost/{:"hello"}

Expected:
Value in latest value:

http://localhost/