import java.util.regex.*;
 
class Ideone {
	public static void main (String[] args) throws java.lang.Exception {
		// pattern that captures quoted strings ignoring all escaped quotes
		Pattern p = Pattern.compile("\"[^\"\\\\]*(?:\\\\.[^\"\\\\]*)*\"");
 
		String data1 = "\"Test Line wo line break\", \"Test Line \nwith line break\"\n\"Test Line2 wo line break\", \"Test Line2 \nwith line break\"\n";
 
		// functional code to get all quotes strings and then remove all line 
		// breaks from matched substrings
		String repl = p.matcher(data1).replaceAll(m -> m.group().replaceAll("\\R+", ""));
 
		System.out.println(repl);
	}
}

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