code: public static String underscoreToCamelCase(final String undescoredString) {
  
          // Split the string for each underscore
          final String[] parts = undescoredString.split(CASE_SEPARATOR);
          final StringBuilder camelCaseString = new StringBuilder(undescoredString.length());
          camelCaseString.append(parts[0].toLowerCase(Locale.getDefault()));
  
          // Skip the first part already added
          for (int i = 1; i < parts.length; i++) {
              // First letter to upper case
              camelCaseString.append(parts[i].substring(0, 1).toUpperCase(Locale.getDefault()));
              // Others to lower case
              camelCaseString.append(parts[i].substring(1).toLowerCase(Locale.getDefault()));
          }
          return camelCaseString.toString();
  
      }
docs: Convert A_STRING_UNDESCORED into aStringUnderscored.
  
  @param undescoredString the string to convert
  
  @return the string with camelCase