Issue with persistent line break with fun("", {})

Description

Let's assume the following code with a persistent line break

list(
foo, bar)
# Which gets formatted as
list(
  foo,
  bar
)

If I switch bar for an expression, it's still formatted as expected:

list(
foo, {bar})
# gets formatted as
list(
  foo,
  {
    bar
  }
)

But if ever foo is a text string, the persistent line break is removed:

list(
"foo", {bar})
# gets formatted as
list("foo", {
  bar
})

only in cases where {} is the second argument:

list(
  "foo","bar",{bar}
)
# gets formatted as
list(
  "foo",
  "bar",
  {
    bar
  }
)

Is this an intended behavior?

Thanks.

Start by reproducing the supplied R formatting examples and compare the behavior when the first argument is a string versus another expression. Trace the formatter entry point responsible for list calls and determine whether the persistent line break is intentional; done means the behavior is clarified and the relevant formatting case is covered consistently.