StringTransform optimization

[productivityindustries]

while using CodeGuru to profile my own code (java lambda with xray), i got a recommendation for an optimization that pointed to class com.amazonaws.xray.utils.StringTransform and the repeated compilation of REGEX.

The optimization would be very straightforward and it performs 25% faster.

public class StringTransform {

  private static final Pattern REGEX = Pattern.compile("([a-z])([A-Z]+)");
  private static final String REPLACE = "$1_$2";

  public static String toSnakeCase(String camelCase) {
    return REGEX.matcher(camelCase).replaceAll(REPLACE).toLowerCase();
  }
}

[willarmiros]

@productivityindustries thanks for doing this profile! If you'd like to open a PR with the optimization we'd be happy to approve.