Not sure what T extends 'getFullDomain' mean in the code below:

const cleanStep: CleanStep = {
  id: '1',
  type: 'clean',

  runAnalyzerAsync: function <T extends 'getFullDomain'>(
    analyzerName: T,
    params: AnalyzerRequestParamsMap[T]
  ): Promise<AnalyzerResponse<GetFullDomainResult, GetFullDomainErrors>> {
    if (params.columnName === 'col8') {
      return Promise.resolve(analyzerErrorResponse);
    }
    return Promise.resolve(getAnalyZerResponse(params.columnName));
  },
  getOutputSchemaAsync: function (): Promise<readonly Column[]> {
    return Promise.resolve([]);
  },
  selectAsync: function (): Promise<SelectResponse> {
    throw new Error('Function not implemented.');
  },
};

Does it mean that the AnalyzerRequestParamsMaptype can only take type of T and T has to be a derived type of getFullDomain ?

And I should in some where find the definition of getFullDomain type?