code: public static String buildPath(String first, String... parts) {
          StringBuilder result = new StringBuilder(first);
  
          for (String part : parts) {
              if (result.length() == 0) {
                  if (part.startsWith("/")) {
                      result.append(part.substring(1));
                  } else {
                      result.append(part);
                  }
              } else {
                  if (result.toString().endsWith("/") && part.startsWith("/")) {
                      result.append(part.substring(1));
                  } else if (!result.toString().endsWith("/") && !part.startsWith("/") && !part.isEmpty()) {
                      result.append("/").append(part);
                  } else {
                      result.append(part);
                  }
              }
          }
  
          return result.toString();
      }
docs: Concatenate path parts into a full path, taking care of extra or missing slashes.
  
  @param first the first part.
  @param parts the additional parts.
  @return the concatenated path.