Empty sentence being cached

[yang-er]

When the first call of merge is of empty array, then it will become

MERGE INTO [TenantClassStudents] AS [t]
USING (
    VALUES

) AS [cte] ([ClassId], [StudentId])
    ON ([t].[StudentId] = [cte].[StudentId]) AND ([t].[ClassId] = [cte].[ClassId])
WHEN NOT MATCHED BY TARGET
    THEN INSERT ([StudentId], [ClassId]) VALUES ([cte].[StudentId], [cte].[ClassId]);

However, after this operation, calling this merge with an non-empty will carry on all the sentences, but the SQL command text is still empty.

[yang-er]

Merge 100 items then 25 items, the 100-item sentence will be cached.