Use the :g command in vim with multiple actions

How can I use something like this?

:g/^$/kJ

Here kJ are two commands, instead of just one (like 'd')

My concrete example: I have multiple lines looking like this

queryBuilder
    .append("xyz");

and I want to make them look like this:

queryBuilder.append("xyz");

So what I want to do for each line is

:g/^[\t]*\..*$/kJx

which matches the correct pattern but seems to execute only k.

Are other vim commands suitable here? How would you perform this task?