allow either to replace or complete provider contacts

lib/AccountManager/WebRequest.pm

@@ -262,12 +262,20 @@ sub req_select_sp {
         }
     }
 
-    # replace metadata contacts from configuration contacts if defined
+    # override metadata contacts if needed
     my $entity = $self->{in}->{sp_entityid};
     my $contacts =
         $self->{configuration}->{$entity}->{contacts} ||
         $self->{configuration}->{service}->{contacts};
-    $provider->contacts(split(/, */, $contacts)) if $contacts;
+    if ($contacts) {
+        if ($contacts =~ /^\+(.+)/) {
+            # complement original contacts
+            $provider->contacts($provider->contacts(), split(/, */, $1));
+        } else {
+            # replace original contacts
+            $provider->contacts(split(/, */, $contacts));
+        }
+    }
 
     $self->{out}->{provider} = $provider;
     $self->{out}->{subtitle} = 'Select your Service Provider';
@@ -303,12 +311,20 @@ sub req_generate_token {
         return;
     }
 
-    # replace metadata contacts from configuration contacts if defined
+    # override metadata contacts if needed
     my $entity = $self->{in}->{sp_entityid};
     my $contacts =
         $self->{configuration}->{$entity}->{contacts} ||
         $self->{configuration}->{service}->{contacts};
-    $provider->contacts(split(/, */, $contacts)) if $contacts;
+    if ($contacts) {
+        if ($contacts =~ /^\+(.+)/) {
+            # complement original contacts
+            $provider->contacts($provider->contacts(), split(/, */, $1));
+        } else {
+            # replace original contacts
+            $provider->contacts(split(/, */, $contacts));
+        }
+    }
 
     ## Check that email_address is a known contact for this SP
     unless ($provider->is_contact($self->{in}->{email_address}))