src/Observers/EntityAttributeObserver.php
protected function getAttributeGroupByEntityTypeCodeAndAttributeSetNameAndAttributeGroupName($entityTypeCode, $attributeSetName, $attributeGroupName)
    {
        return $this->getSubject()->getAttributeGroupByEntityTypeCodeAndAttributeSetNameAndAttributeGroupName($entityTypeCode, $attributeSetName, $attributeGroupName);
    }
protected function getAttributeGroupByEntityTypeCodeAndAttributeSetNameAndAttributeGroupName($entityTypeCode, $attributeSetName, $attributeGroupName)
    {
        return $this->getSubject()->getAttributeGroupByEntityTypeCodeAndAttributeSetNameAndAttributeGroupName($entityTypeCode, $attributeSetName, $attributeGroupName);
    }
Return's the attribute group with the passed attribute set/group name.

@param string $entityTypeCode     The entity type code of the requested attribute group
@param string $attributeSetName   The name of the requested attribute group's attribute set
@param string $attributeGroupName The name of the requested attribute group

@return array The EAV attribute group
@throws \Exception Is thrown, if the attribute group with the passed attribute set/group name is not available