code: void appendBuilders(List<RoutesBuilder> list) {
          for (Bean<?> bean : manager.getBeans(RoutesBuilder.class, ANY)) {
              logger.trace("Found RouteBuilder bean {}", bean);
  
              // certain beans should be ignored
              if (shouldIgnoreBean(bean)) {
                  logger.debug("Ignoring RouteBuilder {}", bean);
                  continue;
              }
  
              if (!isFilteredClass(bean)) {
                  logger.debug("Ignoring filtered RouteBuilder {}", bean);
                  continue;
              }
  
              logger.debug("Adding instantiated RouteBuilder {}", bean);
              Object instance = manager.getReference(bean, RoutesBuilder.class, manager.createCreationalContext(bean));
              list.add((RoutesBuilder) instance);
          }
      }
docs: Appends all the {@link org.apache.camel.builder.RouteBuilder} bean instances that can be found in the manager.