Searching for a process definition by its name does not work. Here is the code in ProcessDefinitionQueryImpl:

if (nameLike!=null)

{ appendWhereClause("idProperty.objectName like '"+nameLike+"' ", hql); }

if (name!=null)

{ appendWhereClause("idProperty.objectName = '"+nameLike+"' ", hql); }

As you can see, it is using the "nameLike" property when you specify the "name" property.