unescapeJava
Unescapes any Java literals found in the String. For example, it will turn a sequence of '\' and 'n' into a newline character, unless the '\' is preceded by another '\'.
This can be replaced by String::translateEscapes in JDK 13
Return
a new unescaped String, null if null string input
Parameters
input
the String to unescape, may be null