Possible null safety issue: Symbol defined in legacy library errors

[jimmyff]

Hi, I'm getting this weird errors when I try to use this library. Pub says it supports null safety so maybe it's an issue at my end?

{
	"resource": "/d:/dev/dart/os_app/lib/_exports.dart",
	"owner": "_generated_diagnostic_collection_name_#3",
	"code": "export_legacy_symbol",
	"severity": 8,
	"message": "The symbol 'ExpandingDotsEffect' is defined in a legacy library, and can't be re-exported from a library with null safety enabled.\nTry removing the export or migrating the legacy library.",
	"source": "dart",
	"startLineNumber": 100,
	"startColumn": 8,
	"endLineNumber": 100,
	"endColumn": 66
}

{
	"resource": "/d:/dev/dart/os_app/lib/_exports.dart",
	"owner": "_generated_diagnostic_collection_name_#3",
	"code": "export_legacy_symbol",
	"severity": 8,
	"message": "The symbol 'SwapEffect' is defined in a legacy library, and can't be re-exported from a library with null safety enabled.\nTry removing the export or migrating the legacy library.",
	"source": "dart",
	"startLineNumber": 100,
	"startColumn": 8,
	"endLineNumber": 100,
	"endColumn": 66
}

{
	"resource": "/d:/dev/dart/os_app/lib/_exports.dart",
	"owner": "_generated_diagnostic_collection_name_#3",
	"code": "export_legacy_symbol",
	"severity": 8,
	"message": "The symbol 'ColorTransitionEffect' is defined in a legacy library, and can't be re-exported from a library with null safety enabled.\nTry removing the export or migrating the legacy library.",
	"source": "dart",
	"startLineNumber": 100,
	"startColumn": 8,
	"endLineNumber": 100,
	"endColumn": 66
}

{
	"resource": "/d:/dev/dart/os_app/lib/_exports.dart",
	"owner": "_generated_diagnostic_collection_name_#3",
	"code": "export_legacy_symbol",
	"severity": 8,
	"message": "The symbol 'ScaleEffect' is defined in a legacy library, and can't be re-exported from a library with null safety enabled.\nTry removing the export or migrating the legacy library.",
	"source": "dart",
	"startLineNumber": 100,
	"startColumn": 8,
	"endLineNumber": 100,
	"endColumn": 66
}

etc