STYLE: FUTURE REMOVE GradientImageFilter::OverrideBoundaryCondition(T *)

Deprecated (`ITK_FUTURE_LEGACY_REMOVE`) the overload of
`GradientImageFilter::OverrideBoundaryCondition` that has a raw pointer as
parameter, in favor of the overload that has a `unique_ptr` as parameter.

Author: N-Dekker

Modules/Filtering/ImageGradient/include/itkGradientImageFilter.h

@@ -141,9 +141,12 @@ class ITK_TEMPLATE_EXPORT GradientImageFilter : public ImageToImageFilter<TInput
   }
 #endif
 
-  /** Allows to change the default boundary condition */
-  void
+#ifndef ITK_FUTURE_LEGACY_REMOVE
+  /** Allows to change the default boundary condition
+   * \note This filter takes ownership of the specified boundary condition object. */
+  [[deprecated("Deprecated in favor of `OverrideBoundaryCondition(std::unique_ptr<BoundaryConditionType>)`.")]] void
   OverrideBoundaryCondition(BoundaryConditionType * boundaryCondition);
+#endif
 
   /** Allows to change the default boundary condition */
   void

Modules/Filtering/ImageGradient/include/itkGradientImageFilter.hxx

@@ -37,13 +37,15 @@ GradientImageFilter<TInputImage, TOperatorValueType, TOutputValueType, TOutputIm
   this->ThreaderUpdateProgressOff();
 }
 
+#ifndef ITK_FUTURE_LEGACY_REMOVE
 template <typename TInputImage, typename TOperatorValueType, typename TOutputValue, typename TOutputImage>
 void
 GradientImageFilter<TInputImage, TOperatorValueType, TOutputValue, TOutputImage>::OverrideBoundaryCondition(
   BoundaryConditionType * boundaryCondition)
 {
   m_BoundaryCondition.reset(boundaryCondition);
 }
+#endif
 
 template <typename TInputImage, typename TOperatorValueType, typename TOutputValue, typename TOutputImage>
 void