Any usage (part, item etc.) "directly" owned by a package is not a composite (does not have
isComposite=true) – and even if you omit the ref keyword – because a package is not an occurrence:
SysML2.0: 'A composite usage must be featured by an occurrence (such as an item, part or action ...)'
And even if the symbol header displays as «part» (not «ref part»).
Indeed, the ref keyword in this case is redundant, and Cameo removes it on sync.
BTW: Technically speaking, in SysMLv2 a package does not "directly own" a part usage but in fact has a reified owning membership relationship, but informally we may say that the package "owns" elements.
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