It's limitation of interpolated string literals. You can use the s""" blah """
form to get enclosed double quotes.
To wit:
scala> val bar = "p1"
bar: String = p1
scala> val baz = "p2"
baz: String = p2
scala> val str = s"""foo="-param1$bar -param2$baz\""""
str: String = foo="-param1p1 -param2p2"