private Collection<ConfigAttribute> getAttributes(final MethodDescriptor<?, ?> method) {
        return this.accessMap.getOrDefault(method, this.defaultAttributes);
    }
A {@link GrpcSecurityMetadataSource} for manual configuration. For each {@link MethodDescriptor gRPC method} a
{@link AccessPredicate} can be defined, that checks whether the user is authenticated and has access. This metadata
source only works if an {@link AccessDecisionManager} is configured with an {@link AccessPredicateVoter}.

<p>
<b>Note:</b> This instance is initialized with {@link AccessPredicate#denyAll() deny all} as default.
</p>

@author Daniel Theuke (daniel.theuke@aequitas-software.de)
grpc-server-spring-boot-starter/src/main/java/net/devh/boot/grpc/server/security/check/ManualGrpcSecurityMetadataSource.java