HiveUnionPullUpConstantsRule produces an invalid plan when pulling up constants for nullable fields

java.lang.AssertionError: Cannot add expression of different type to set:
set type is RecordType(JavaType(class java.lang.Integer) f1, JavaType(int) NOT NULL f2) NOT NULL
expression type is RecordType(JavaType(int) NOT NULL f1, JavaType(int) NOT NULL f2) NOT NULL
set is rel#38:HiveUnion.(input#0=HepRelVertex#35,input#1=HepRelVertex#35,all=true)
expression is HiveProject(f1=[1], f2=[$0])
  HiveUnion(all=[true])
    HiveProject(f2=[$1])
      HiveProject(f1=[$0], f2=[$1])
        HiveFilter(condition=[=($0, 1)])
          LogicalTableScan(table=[[]])
    HiveProject(f2=[$1])
      HiveProject(f1=[$0], f2=[$1])
        HiveFilter(condition=[=($0, 1)])
          LogicalTableScan(table=[[]])