Hibernate 5.1 has option for specifying fetch groups for lazy fields. (Of course this requires byte code enhancement). There is documentation for showing how to specify fetch group using @LazyGroup but could not find anything to mark lazy group in hbm.

@Basic( fetch = FetchType.LAZY )
@LazyGroup( "lobs" )
private String name;

hbm : <property name="name" type="string" lazy="true" ???="lobs">
<column name="name" />
</property>

what would be the attribute name to replace "???" ?. lazygroup="lobs" does not work.

There is no such thing in HBM. The annotations are to be the preferred from Hibernate 5.0 onwards.

So the hbm would be phased out!!!
HBMs allowed to keep domain java classes separate from hibernate specific configurations and mappings. Now these classes would be hardwired with hibernate dependencies and it would create problems in migrating to hibernate 5 from earlier versions. Request to consider supporting hbms with new features.

It's not decided what exactly will happen. It's possible to provide an extension to JPA orm.xml mapping too. The reason for this is that it takes more resources to maintain two mapping approaches.