Condition To Check For More Than One string from http response

Hi there is another one here in the image above, so strJson is my http response variable, the response contains “lineOfBusinessSystem” string and the string needs to appear once if twice or more then I do another activity
Please assist on how I should write it in the IF statement.
There is also a value for that string:


I have declared that value as ‘LOB’(string )
So if that string appears more than once or that value then I do something else

made the condition like this but then it returned an error :
if: Value cannot be null (Parameter ‘source’)

Anyone please assist