docs: protected String getIsolationLevelAsString()
      {
          if (defaultIsolationLevel == IL_READ_UNCOMMITTED)
          {
              return LITERAL_IL_READ_UNCOMMITTED;
          }
          else if (defaultIsolationLevel == IL_READ_COMMITTED)
          {
              return LITERAL_IL_READ_COMMITTED;
          }
          else if (defaultIsolationLevel == IL_REPEATABLE_READ)
          {
              return LITERAL_IL_REPEATABLE_READ;
          }
          else if (defaultIsolationLevel == IL_SERIALIZABLE)
          {
              return LITERAL_IL_SERIALIZABLE;
          }
          else if (defaultIsolationLevel == IL_OPTIMISTIC)
          {
              return LITERAL_IL_OPTIMISTIC;
          }
          return LITERAL_IL_READ_UNCOMMITTED;
      }