In both cases this is due to the fact that the negation sign is handled seperately in the AST tree (as a UNARY_MINUS). This works out fine in the resulting SQL in the majority of cases.

However it breaks down specifically in the case of the MIN_VALUEs because of numeric overflow issues trying to parse the numbers. For both Integer and Long: ( MAX_VALUE == ( -MIN_VALUE ) - 1 ).

For example, for Integer: MIN_VALUE = -2e31 while MAX_VALUE = 2e31-1. Therefore the HQL:
("from Animal a where a.integer = " + Integer.MIN_VALUE) will fail because the negation sign is removed leaving 2e31 to be processed as the numeric literal value, which is bigger than Integer.MAX_VALUE.

I added a workaround while fixing such that a NumberFormatException on parsing an Integer will attempt to parse as a Long in anticipation that the format issue might be an overflow issue. Thus, really only Long.MIN_VALUE is currently a problem.