Numbers with zero fractional should be considered valid for `integer`

[wezleytsai]

According to the spec, a JSON number with zero fractional part, such as 5.0, is considered compliant to the schema type integer. See https://json-schema.org/understanding-json-schema/reference/numeric. JSON-java maps any number with a fractional, even if 0, to BigDecimal, but this library requires an Integer and throws expected type: Integer, found: BigDecimal based on the type alone. IMO this library should evaluate any Number and validate based on whether it is an integer.

Here is a minimal repo that reproduces the validation exception:
https://github.com/wezleytsai/json-schema/blob/master/src/main/java/Main.java