private Region<Object/* Integer or EnumCode */, Object/* PdxType or enum info */> getIdToType() {
    if (idToType != null) {
      return idToType;
    } else {
      if (cache.getPdxPersistent() && cache.getCacheConfig().pdxDiskStoreUserSet) {
        throw new PdxInitializationException(
            "PDX registry could not be initialized because the disk store "
                + cache.getPdxDiskStore() + " was not created.");
      } else {
        throw new PdxInitializationException("PDX registry was not initialized.");
      }
    }
  }
The region where the PDX metadata is stored. Because this region is transactional for our
internal updates but we don't want to participate in the users transactions, all operations on
this region must suspend any existing transactions with suspendTX/resumeTX.
geode-core/src/main/java/org/apache/geode/pdx/internal/PeerTypeRegistration.java