code: public static Lookup get() {
          if (LOOKUP != null) {
              return LOOKUP;
          }
          synchronized (Lookup.class) {
              // allow for override of the Lookup.class
              String overrideClassName = System.getProperty(Lookup.class.getName());
              ClassLoader l = Thread.currentThread().getContextClassLoader();
              try {
                  if (overrideClassName != null && !"".equals(overrideClassName)) {
                      LOOKUP = (Lookup) Class.forName(overrideClassName, true, l).newInstance();
                  } else {
                      LOOKUP = new Lookup();
                  }
              } catch (Exception e) {
                  // ignore
              }
              // ServiceLoader and CDI are used by defaults, important that
              // CDI is used first so that beans are enabled for injection
              CdiLookup cdiLookup = new CdiLookup();
              LOOKUP.lookupProviders.add(cdiLookup);
              ServiceLoaderLookup serviceLoaderLookup = new ServiceLoaderLookup();
              LOOKUP.lookupProviders.add(serviceLoaderLookup);
              // Use ServiceLoader to find other LookupProviders
              Collection<LookupProvider> providers = serviceLoaderLookup
                      .lookupAll(LookupProvider.class);
              LOOKUP.lookupProviders.addAll(providers);
          }
  
          return LOOKUP;
      }
docs: Acquire the Lookup registry.
  
  @return The lookup registry.