code: @PUT
      @Path("/guid/{guid}/classifications")
      @Produces(Servlets.JSON_MEDIA_TYPE)
      public void updateClassification(@PathParam("guid") final String guid, List<AtlasClassification> classifications) throws AtlasBaseException {
          AtlasPerfTracer perf = null;
  
          try {
              if (AtlasPerfTracer.isPerfTraceEnabled(PERF_LOG)) {
                  perf = AtlasPerfTracer.getPerfTracer(PERF_LOG, "EntityREST.updateClassification(" + guid + ")");
              }
  
              if (StringUtils.isEmpty(guid)) {
                  throw new AtlasBaseException(AtlasErrorCode.INSTANCE_GUID_NOT_FOUND, guid);
              }
  
              entitiesStore.updateClassifications(guid, classifications);
  
          } finally {
              AtlasPerfTracer.log(perf);
          }
      }
docs: Updates classifications to an existing entity represented by a guid.
  @param  guid globally unique identifier for the entity
  @return classification for the given entity guid