As mentioned by aschackmull during review, StatementExpression as defined
by the JLS only lists possible types of expressions, it does _not_ specify
that their value is discarded. Therefore, for example any method call could
be considered a StatementExpression.
The name ValueDiscardingExpr was chosen as replacement because the JLS uses
the phrase "if the expression has a value, the value is discarded" multiple
times.
