code: @BsonIgnore @Nullable
      public String getDatabaseName() {
          if (namespaceDocument == null) {
              return null;
          }
          if (!namespaceDocument.containsKey("db")) {
              return null;
          }
          return namespaceDocument.getString("db").getValue();
      }
docs: Returns the database name
  
  @return the databaseName. If the namespaceDocument is null or if it is missing the 'db' key, then this will
  return null.
  @since 3.8