docs: public String getDatabasePlatformClassName(PUInfoImpl pui) {
          SessionLog traceLogger = new TraceLog();
  
          Properties properties = pui.getProperties();
          String productName = properties.getProperty(PersistenceUnitProperties.SCHEMA_DATABASE_PRODUCT_NAME);
  
          String vendorNameAndVersion = null;
          // check persistent properties
          if (productName != null) {
              vendorNameAndVersion = productName;
  
              String majorVersion = properties.getProperty(PersistenceUnitProperties.SCHEMA_DATABASE_MAJOR_VERSION);
              if (majorVersion != null) {
                  vendorNameAndVersion += majorVersion;
                  String minorVersion = properties.getProperty(PersistenceUnitProperties.SCHEMA_DATABASE_MINOR_VERSION);
                  if (minorVersion != null) {
                      vendorNameAndVersion += minorVersion;
                  }
              }
          } else {
              vendorNameAndVersion = getVendorNameAndVersion(pui.getJtaDataSource());
              if (vendorNameAndVersion == null) {
                  getVendorNameAndVersion(pui.getNonJtaDataSource());
              }
          }
  
          return DBPlatformHelper.getDBPlatform(vendorNameAndVersion, traceLogger);
      }