fix "is undef" test

diff --git a/sdk/perl/lib/Arvados/ResourceMethod.pm b/sdk/perl/lib/Arvados/ResourceMethod.pm
index 52334d7fe2f8e735d62c0982bb11e58048446169..76c1ac86910844ab8a409b8ab10b4486585d76dc 100644 (file)
--- a/sdk/perl/lib/Arvados/ResourceMethod.pm
+++ b/sdk/perl/lib/Arvados/ResourceMethod.pm
@@ -50,7 +50,7 @@ sub execute
                     if (!exists $given_params{$param_name}->{$property_name}) {
                         ;
                     }
-                    elsif ($given_params{$param_name}->{$property_name} eq undef) {
+                    elsif (!defined $given_params{$param_name}->{$property_name}) {
                         $param_value{$property_name} = JSON::null;
                     }
                     elsif ($property->{'type'} eq 'boolean') {