UE4 Plugin Link Error:

Error   LNK2019 unresolved external symbol "private: static class UClass * __cdecl UMyComponent::GetPrivateStaticClass(void)" (?GetPrivateStaticClass@UMyComponent@@CAPEAVUClass@@XZ) referenced in function "class UMyComponent * __cdecl NewObject<class UMyComponent>(class UObject *)" (??$NewObject@VUMyComponent@@@@YAPEAVUMyComponent@@PEAVUObject@@@Z)  ClimbWall   

Reason:
Maybe you removed UE4’s macro in your header.

Solution:
Add UE4 stylized macro in header, e.g.:

UCLASS()
class TESTPLUGIN_API UMyComponent : public UActorComponent
{
    GENERATED_BODY()
}