Method put

src/main/java/com/amazon/ion/IonStruct.java:123–123

Puts a new field in this struct, replacing all existing fields with the same name. If child == null then all existing fields with the given name will be removed. If this is null.struct and child != null then this becomes a single-field struct. The effect of this

(String fieldName, IonValue child)

     *   if {@code element} is an {@link IonDatagram}.
     */
    public void put(String fieldName, IonValue child)
        throws ContainedValueException;