@NotNull public static String appendToPathEnvVar(@Nullable String source,@NotNull String value){
  if (StringUtil.isEmpty(source))   return value;
  Set<String> paths=Sets.newHashSet(source.split(File.pathSeparator));
  return !paths.contains(value) ? source + File.pathSeparator + value : source;
}

@ NotNull public static String appendToPathEnvVar ( @ Nullable String source , @ NotNull String value ) { if ( StringUtil . isEmpty ( source ) ) return value ; Set < String > paths = Sets . newHashSet ( source . split ( File . pathSeparator ) ) ; return ! paths . contains ( value ) ? source + File . pathSeparator + value : source ; }
appends a value to the end os a path - like environment variable , using system - dependent path separator .
