The method getLevel() does not exist on Jackal\ImageMerge\Comman...\CommandOptionInterface. It seems like you code against a sub-type of Jackal\ImageMerge\Comman...\CommandOptionInterface such as Jackal\ImageMerge\Comman...ions\LevelCommandOption.
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Ignorable by Annotation
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If this is a false-positive, you can also ignore this issue in your code via the ignore-call annotation