code: public AssertSoapFaultBuilder faultDetailResource(Resource resource, Charset charset) {
          try {
              action.getFaultDetails().add(FileUtils.readToString(resource, charset));
          } catch (IOException e) {
              throw new CitrusRuntimeException("Failed to read fault detail resource", e);
          }
          return this;
      }
docs: Expect fault detail from file resource.
  @param resource
  @param charset
  @return