code: public ManualGrpcSecurityMetadataSource set(final MethodDescriptor<?, ?> method, final AccessPredicate predicate) {
          requireNonNull(method, "method");
          this.accessMap.put(method, wrap(predicate));
          return this;
      }
docs: Set the given access predicate for the given method. This will replace previously set predicates.
  
  @param method The method to protect with a custom check.
  @param predicate The predicate used to check the {@link Authentication}.
  @return This instance for chaining.
  @see #setDefault(AccessPredicate)