code: static MetaBean lookup(Class<?> cls) {
          MetaBean meta = META_BEANS.get(cls);
          if (meta == null) {
              return metaBeanLookup(cls);
          }
          return meta;
      }
docs: Gets the meta-bean for a class.
  <p>
  This only works for those beans that have registered their meta-beans.
  <p>
  A {@code Class} may use a static initializer block to call {@code register}.
  The edge case where the class is loaded but not initialized is handled
  by forcing the class to be initialized if necessary.
  
  @param cls  the class to get the meta-bean for, not null
  @return the meta-bean, not null
  @throws IllegalArgumentException if unable to obtain the meta-bean