protected BigDecimal resolveMultipleOf(MemberScope<?, ?> member) {
        return this.getSchemaAnnotationValue(member, Schema::multipleOf, multipleOf -> multipleOf != 0)
                .map(BigDecimal::valueOf)
                .orElse(null);
    }
Look-up the value from {@code @Schema(multipleOf = ...)} for the given field/method.

@param member field/method to look-up multipleOf for
@return multipleOf value or null
jsonschema-module-swagger-2/src/main/java/com/github/victools/jsonschema/module/swagger2/Swagger2Module.java