In negotiations with Azul, Sun alleged that Azul infringed Sun patents and misappropriated trade secrets, Azul said. "Sun has repeatedly threatened the company with litigation unless Azul granted Sun part ownership of the company and agreed to pay exorbitant up-front fees and continuing royalties on the sale of Azul products. Attempts to reach an agreement failed when Sun gave Azul an ultimatum: Accept its final proposal or face litigation," the company said.
We can't always just get along, of course. Azul directly competes with Sun's UltraSparc T1s, so there may be a lot of business behind the litigation. It seems, however, that Sun probably has much bigger fish to worry about than Azul.