use strict;
use warnings;

my @chunks = split '"', do{local $/; <DATA>}, -1;

s/(?<=.)\s*\n\s*(?=.)/ /g for @chunks;

print join '"', @chunks;

__DATA__
"boom"
hello "" bill
"baz
         hello
            jock"
"boom2"
 abc "baz2
hello2          
            jock2 "