Denotable

in hot regions, and more spread and digested flowers, a sweet savour may be allowed, denotable from several human expressions, and the practice of the ancients, in putting the dried flowers of the vine into new wine[…]

JDK9 added support for the diamond operator in anonymous classes if the inferred types are denotable. You cannot use the diamond operator with anonymous classes—even in JDK9—if the inferred types are non-denotable.