docs: private Map<String, SignerConfig> buildSignerMap(JsonIndex<SignerConfigJsonHelper, SignerConfig>[] signerIndexes,
                                                       String theme) {
          Map<String, SignerConfig> map = new HashMap<String, SignerConfig>();
          if (signerIndexes != null) {
              for (JsonIndex<SignerConfigJsonHelper, SignerConfig> index : signerIndexes) {
                  String region = index.getKey();
                  SignerConfig prev = map.put(region, index.newReadOnlyConfig());
                  if (prev != null) {
                      log.warn("Duplicate definition of signer for " + theme + " " + index.getKey());
                  }
              }
          }
          return map;
      }