This YANG causes the following error during maven code generation:

Failed to find leafref target: /operations/operation/effort in module enum-leafref

module enum-leafref {
  namespace "urn:donaldh:yang:leafref:bug";
  prefix l;

  typedef action-effort {
    type enumeration {
      enum best-effort {
{{      }}}
      enum exact-match {
{{      }}}}}
{{    }}}
{{  }}}
  container operations {
    list operation {
      key 'effort';
      uses operation-g;
{{    }}}
{{  }}}
  grouping operation-g {
    leaf effort {{{}}
      type action-effort;
{{    }}}
    leaf-list operation {
      type leafref {{{}}
        path '/operations/operation/effort';
{{      }}}
{{    }}}
{{  }}}
}

It is possible to work around the bug by either changing leaf "effort" to be type string or by collapsing grouping "operation-g" into list "operation".