STYLE: Remove SetFixedParameters... functions from BSplineBaseTransform

[N-Dekker]

Removed the protected SetFixedParametersFromTransformDomainInformation() from BSplineBaseTransform, and moved the code of its implementation into the default-constructor of BSplineDeformableTransform, which was the only place where the function was called.

Removed four protected pure virtual member functions from BSplineBaseTransform:

SetFixedParametersGridSizeFromTransformDomainInformation()
SetFixedParametersGridOriginFromTransformDomainInformation()
SetFixedParametersGridSpacingFromTransformDomainInformation()
SetFixedParametersGridDirectionFromTransformDomainInformation()

• Left them implemented by BSplineDeformableTransform, but removed their dummy (empty) implementations from BSplineTransform. They were already made empty by pull request ENH: Refactor BSplineTransform #297 commit 794c82d, Bradley Lowekamp (@blowekamp), 2018.

[greptile-apps]

Greptile Summary

This update removes obsolete BSpline fixed-parameter initialization hooks, keeps the specialized deformable-transform initialization path, and cleans up the stale documentation grouping marker. The documentation grouping is now balanced, and no new issues require action.

Confidence Score: 5/5

Safe to merge.

No outstanding findings remain. The previously reported documentation issue was fully addressed: N-Dekker removed the stale terminator, and the remaining documentation group has matching start and end markers.

_{Reviews (2): Last reviewed commit: "STYLE: Remove SetFixedParameters... func..." | Re-trigger Greptile}

[N-Dekker]

External subclasses that retain override declarations for the four removed grid-information hooks no longer compile.

BSplineBaseTransform was never meant to be used as base class of external subclasses. It was just meant to be the common base class of ITK's own BSplineTransform and BSplineDeformableTransform. As suggested by its documentation at

ITK/Modules/Core/Transform/include/itkBSplineBaseTransform.h

Line 29 in 2782335

* \brief A base class with common elements of BSplineTransform and BSplineDeformableTransform

Which says about BSplineBaseTransform:

A base class with common elements of BSplineTransform and BSplineDeformableTransform

So then I think we shouldn't worry about breaking support for some hypothetical external subclasses.

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For the record, BSplineBaseTransform was introduced by commit 937439c, "STYLE: Common base class for BSpline*Transforms", Nov 4, 2011, by Hans Johnson (@hjmjohnson).