The Java Language Specification, Third Edition

EXPRESSIONS Compile-Time Step 2: Determine Method Signature 15.12.2
G. Substituting the type expression U for S will then yield a (non-wildcard) invocation of
H, H[S = U], that is a supertype of G. For example, in the simplest instance, U1
might be S, in which case we have G F = G for some type expression W. Since W is a type expression
(and not a wildcard type argument), it must be the case that W=U,by the non-variance
of parameterized types.
DISCUSSION
✦ Otherwise, if A is of the form G, this
algorithm is applied recursively to the constraint W >> U.
DRAFT
We have A = G