fix(field-resolver): re-add support for isser methods

Author: Kocal

UPGRADE-0.13.md

@@ -23,7 +23,7 @@ The new `default_field_resolver` config entry accepts callable service id.
 Stop using internally `symfony/property-access` package
 since it was a bottleneck to performance for large schema.
 
-Array access and camelize getter are supported but isser, hasser,
+Array access and camelize getter/isser are supported but hasser,
 jQuery style (e.g. `last()`) and "can" property accessors
 are no more supported out-of-the-box,
 please implement a custom resolver if these accessors are needed.

src/Resolver/FieldResolver.php

@@ -24,6 +24,8 @@ public static function valueFromObjectOrArray($objectOrArray, $fieldName)
         } elseif (\is_object($objectOrArray)) {
             if (null !== $getter = self::guessObjectMethod($objectOrArray, $fieldName, 'get')) {
                 $value = $objectOrArray->$getter();
+            } elseif (null !== $getter = self::guessObjectMethod($objectOrArray, $fieldName, 'is')) {
+                $value = $objectOrArray->$getter();
             } elseif (isset($objectOrArray->$fieldName)) {
                 $value = $objectOrArray->$fieldName;
             }