Description

This PR fixes mutable calculate_serialized_size of a size-three optional type. XCDR2 EMHEADER size wrongly computed (4 bytes) for mutable optional field with size different from 1, 2, 4 or 8. It should have a 8 bytes EMHEADER.

@final
struct FinalSizeThree
{
    octet a;
    octet b;
    octet c;
};

@mutable
struct RegressionType
{
    @optional FinalSizeThree opt_fin_size_three;
};

@Mergifyio backport 2.2.x

Contributor Checklist

• Commit messages follow the project guidelines.
• The code follows the style guidelines of this project.
• Tests that thoroughly check the new feature have been added/Regression tests checking the bug and its fix have been added; the added tests pass locally
• N/A Any new/modified methods have been properly documented using Doxygen.
• Changes are backport compatible: they do NOT break ABI nor change library core behavior.
• Changes are API compatible.
• N/A New feature has been added to the versions.md file (if applicable).
• Applicable backports have been included in the description.

Reviewer Checklist

• The PR has a milestone assigned.
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• Check contributor checklist is correct.
• Check CI results: changes do not issue any warning.
• Check CI results: CI pass and failing tests are unrelated with the changes.