code: public static Builder from(Reader swaggerReader) {
          Validate.notNull(swaggerReader, "swaggerReader must not be null");
          Swagger swagger;
          try {
              swagger = new SwaggerParser().parse(IOUtils.toString(swaggerReader));
          } catch (IOException e) {
              throw new RuntimeException("Swagger source can not be parsed", e);
          }
          if (swagger == null)
              throw new IllegalArgumentException("Swagger source is in a wrong format");
  
          return new Builder(swagger);
      }
docs: Creates a Swagger2MarkupConverter.Builder from a given Swagger YAML or JSON reader.
  
  @param swaggerReader the Swagger YAML or JSON reader.
  @return a Swagger2MarkupConverter