Test17_HM_B Output

"...\java" ...Test17_HM_B
Size    :1
Elements : {1=(this Map)}

Size    :1
Elements : {2=(this Map)}

Size    :2
Exception in thread "main" java.lang.StackOverflowError
    at java.util.AbstractMap.toString(AbstractMap.java:547)
    at java.lang.String.valueOf(String.java:2994)
    at java.lang.StringBuilder.append(StringBuilder.java:131)
    at java.util.AbstractMap.toString(AbstractMap.java:559)
    at java.lang.String.valueOf(String.java:2994)
    at java.lang.StringBuilder.append(StringBuilder.java:131)
    at java.util.AbstractMap.toString(AbstractMap.java:559)
    at java.lang.String.valueOf(String.java:2994)
    at ...
               [ Lots of these, repeated, omitted from here.  ;-> ]
    at ...
    at java.lang.String.valueOf(String.java:2994)
    at java.lang.StringBuilder.append(StringBuilder.java:131)
    at java.util.AbstractMap.toString(AbstractMap.java:559)
    at java.lang.String.valueOf(String.java:2994)
    at java.lang.StringBuilder.append(StringBuilder.java:131)
    at java.util.AbstractMap.toString(AbstractMap.java:559)
    at java.lang.String.valueOf(String.java:2994)
    at java.lang.StringBuilder.append(StringBuilder.java:131)
    at java.util.AbstractMap.toString(AbstractMap.java:559)

Process finished with exit code 1