fix(YamlConverter): respect form="unqualified" on individual elements in getElementNamespace

[XenosEleatikos]

Problem

YamlConverter::getElementNamespace assigns a namespace to an element even when that element explicitly declares form="unqualified" in the XSD.

The buggy condition:

protected function getElementNamespace(Schema $schema, ElementItem $element)
{
    if ($element->getSchema()->getTargetNamespace() &&
        ($schema->getElementsQualification()   // ← this OR-branch is the bug
            || ($element instanceof Element && $element->isQualified())
            || !$element->isLocal())
    ) {
        return $element->getSchema()->getTargetNamespace();
    }
    return null;
}

When the containing schema has elementFormDefault="qualified", $schema->getElementsQualification() returns true, which short-circuits the entire condition. This means an element that explicitly declares form="unqualified" still gets a namespace entry in the generated JMS YAML metadata — and is then serialized with a namespace prefix by JMS Serializer, violating the XSD contract.

The xsd-reader correctly reads form="unqualified" and calls setQualified(false) on the element. That correct result is silently overridden by the OR condition.

Reproducer

XSD with elementFormDefault="qualified" and a local element that overrides with form="unqualified":

<!-- parent schema: elementFormDefault="qualified" -->
<xs:complexType name="CodeType">
  <xs:sequence>
    <xs:element name="code" type="xs:token"           form="unqualified"/>
    <xs:element name="name" type="xs:normalizedString" form="unqualified" minOccurs="0"/>
  </xs:sequence>
</xs:complexType>

Generated YAML (wrong):

code:
    xml_element:
        namespace: 'urn:example:schema'   # should not be here
name:
    xml_element:
        namespace: 'urn:example:schema'   # should not be here

This causes JMS Serializer to produce <ns:code> and <ns:name> instead of <code> and <name>, which validators reject.

Fix

Remove $schema->getElementsQualification() from the OR condition. $element->isQualified() already incorporates the schema-level elementFormDefault as a fallback when no explicit form attribute is present, so the removed check was both redundant and incorrect.

-    protected function getElementNamespace(Schema $schema, ElementItem $element)
+    protected function getElementNamespace(Schema $_schema, ElementItem $element)
     {
         if ($element->getSchema()->getTargetNamespace() &&
-            ($schema->getElementsQualification() || ($element instanceof Element && $element->isQualified()) || !$element->isLocal())
+            (($element instanceof Element && $element->isQualified()) || !$element->isLocal())
         ) {

Behaviour matrix

Schema elementFormDefault	Element form attribute	Before	After
qualified	(none)	namespace set ✓	namespace set ✓
qualified	form="unqualified"	namespace set ✗	no namespace ✓
qualified	form="qualified"	namespace set ✓	namespace set ✓
unqualified	(none)	no namespace ✓	no namespace ✓
unqualified	form="qualified"	namespace set ✓	namespace set ✓