code: public static String collToCSVString(Iterable<?> strIterable) {
          StringBuilder buffer = new StringBuilder();
          for (Object value : strIterable) {
              if (buffer.length() > 0) {
                  buffer.append(", ");
              }
              buffer.append(value.toString());
          }
          return buffer.toString();
      }
docs: Turn the given iterable collection into a simple comma-separated value (CSV)
  String. For example, ["abc", "def", "xyz"] becomes "abc, def, xyz". Each member in
  the collection is turned into a string using its toString() method.
  
  @param strIterable   Iterable collection of values.
  @return              Comma-separated list of values.