code: public static String constructCanonicalCompositeIndexName(String[] components) {
          assert components.length > 1;
  
          StringBuilder builder = new StringBuilder(components.length * EXPECTED_AVERAGE_COMPONENT_NAME_LENGTH);
          for (String component : components) {
              if (builder.length() > 0) {
                  builder.append(", ");
              }
              builder.append(component);
          }
          return builder.toString();
      }
docs: Constructs a canonical index name from the given index components.
  <p>
  A canonical name is a comma-separated list of index components with a
  single space character going after every comma.
  <p>
  It's a caller's responsibility to canonicalize individual components
  as specified by {@link #canonicalizeAttribute}.
  
  @param components the index components to construct the canonical index
  name from.
  @return the constructed canonical index name.