Validation error: "No validator could be found for type: java.lang.Integer"
As per the javadoc of NotEmpty, Integer is not a valid type for it to check. It's for Strings and collections. If you just want to make sure an Integer has some value, javax.validation.constraints.NotNull is all you need.
public @interface NotEmpty
Asserts that the annotated string, collection, map or array is not null or empty.
As the question is asked simply use @Min(1) instead of @size on integer fields and it will work.
As stated in problem, to solve this error you MUST use correct annotations. In above problem, @NotBlank or @NotEmpty annotation must be applied on any String field only.
To validate long type field, use annotation @NotNull.