1 John 5:20 - This is he true God

1 John 5:20 (KJV)  And we know that the Son of God is come, and hath given us an understanding, that we may know him that is true, and we are in him that is true, even in his Son Jesus Christ. This is the true God, and eternal life.

In this verse, Jesus is identified as the son of God who reveals "him that is true".

So there is quite obviously two persons in this verse, Jesus and God. No one would argue with that.

Now, given that Jesus says quite explicitly that the Father is the only true God (John 17.3) Then there is no reason to think that "This is he true God" in this verse is not the same person, the Father.

If it wasn't the Father, then it would violate Jesus unitary monotheistic creed and be a total contradiction.