getJoinColumnName example

foreach ($this->class->identifier as $idField) {
            if (! isset($this->class->associationMappings[$idField])) {
                $params[] = $identifier[$idField];
                $types[]  = $this->class->fieldMappings[$idField]['type'];
                $where[]  = $this->quoteStrategy->getColumnName($idField, $this->class, $this->platform);

                continue;
            }

            $params[] = $identifier[$idField];
            $where[]  = $this->quoteStrategy->getJoinColumnName(
                $this->class->associationMappings[$idField]['joinColumns'][0],
                $this->class,
                $this->platform
            );

            $targetMapping = $this->em->getClassMetadata($this->class->associationMappings[$idField]['targetEntity']);
            $targetType    = PersisterHelper::getTypeOfField($targetMapping->identifier[0], $targetMapping, $this->em);

            if ($targetType === []) {
                throw UnrecognizedField::byFullyQualifiedName($this->class->name, $targetMapping->identifier[0]);
            }