The spec says on ExecutableType.IMPLICIT:

IMPLICIT: if @ValidateOnExecution is on a type (class or interface), then it is equivalent to @ValidateOnExecution not being present;

I'd understand this as that the default executable type (CONSTRUCTORS, NON_GETTER_METHODS) should be validated. But the RI also validates getters if @ValidateOnExecution(type=IMPLICIT) is given on the type declaring a getter.

See: * ExecutableTypesTest.testValidationOfConstrainedGetterWithExecutableTypeIMPLICITOnTypeLevel()