Instead of using the current arguments, use the workflows state *afte…

…r* merging arguments

This allows passing in values earlier in the workflow and thereby
decouples the workflow invokers from the workflow execution.

Without this change, the workflow invoker would need to know exactly
which step needs which parameters, which would be a case of tight
integration.

lib/Workflow/Action.pm

@@ -70,15 +70,19 @@ sub validate {
     my @validators = $self->get_validators;
     return unless ( scalar @validators );
 
-    my $context = $wf->context;
+    $action_args //= {};
+    my %all_args = (
+        %{ $wf->context->param() },
+        %{$action_args}
+        );
     foreach my $validator_info (@validators) {
         my $validator    = $validator_info->{validator};
         my $args         = $validator_info->{args};
 
         my @runtime_args = ();
         foreach my $arg ( @{$args} ) {
             if ( $arg =~ /^\$(.*)$/ ) {
-                push @runtime_args, $action_args->{$1};
+                push @runtime_args, $all_args{$1};
             } else {
                 push @runtime_args, $arg;
             }