use more concrete UNO type in SwXTextTableStyle

Change-Id: I19b556a5fc2ee9f475478b16e228aa3670146551
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/150587
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

sw/inc/unostyle.hxx

@@ -18,6 +18,7 @@
  */
 #pragma once
 
+#include <rtl/ref.hxx>
 #include <svl/listener.hxx>
 #include <svl/style.hxx>
 #include "unocoll.hxx"
@@ -267,7 +268,7 @@ class SwXTextTableStyle final : public cppu::WeakImplHelper
     /// Fills m_aCellStyles with SwXTextCellStyles pointing to children of this style.
     void UpdateCellStylesMapping();
     static const CellStyleNameMap& GetCellStyleNameMap();
-    css::uno::Reference<css::style::XStyle> m_aCellStyles[STYLE_COUNT];
+    rtl::Reference<SwXTextCellStyle> m_aCellStyles[STYLE_COUNT];
 public:
     SwXTextTableStyle(SwDocShell* pDocShell, SwTableAutoFormat* pTableAutoFormat);
     /// Create non physical style

sw/source/core/unocore/unostyle.cxx

@@ -4518,7 +4518,8 @@ uno::Any SAL_CALL SwXTextTableStyle::getByName(const OUString& rName)
     if(iter == rMap.end())
         throw css::container::NoSuchElementException();
 
-    return css::uno::Any(m_aCellStyles[(*iter).second]);
+    auto nIdx = (*iter).second;
+    return css::uno::Any(uno::Reference<XInterface>(static_cast<cppu::OWeakObject*>(m_aCellStyles[nIdx].get())));
 }
 
 css::uno::Sequence<OUString> SAL_CALL SwXTextTableStyle::getElementNames()