$ javac Experiment.java
Experiment.java:30: error: method copyRow in class Experiment cannot be applied to given types;
    copyRow(wr.row); // Error
    ^
  required: R
  found: CAP#1
  reason: inference variable R has incompatible bounds
    equality constraints: CAP#1
    lower bounds: Row<CAP#1,CAP#2>
  where R,K are type-variables:
    R extends Row<R,K> declared in method <R,K>copyRow(R)
    K extends Key<K> declared in method <R,K>copyRow(R)
  where CAP#1,CAP#2 are fresh type-variables:
    CAP#1 extends Row<CAP#1,CAP#2> from capture of ?
    CAP#2 extends Key<CAP#2> from capture of ?
Experiment.java:31: error: method copyRow in class Experiment cannot be applied to given types;
    copyRow(upcast(wr.row)); // Error
    ^
  required: R#1
  found: R#2
  reason: inferred type does not conform to upper bound(s)
    inferred: K#3
    upper bound(s): Key<K#3>,Key<K#4>
  where R#1,K#1,R#2,K#2,K#3,K#4 are type-variables:
    R#1 extends Row<R#1,K#1> declared in method <R#1,K#1>copyRow(R#1)
    K#1 extends Key<K#1> declared in method <R#1,K#1>copyRow(R#1)
    R#2 extends Row<R#2,K#2>
    K#2 extends Key<K#2>
    K#3 extends Key<K#4>
    K#4 extends Key<K#3>
2 errors