This rule is defined by the following XPath expression:
//IfStatement[@Else='false']/Statement /IfStatement[@Else='false'] | //IfStatement[@Else='false']/Statement /Block[count(BlockStatement)=1]/BlockStatement /Statement/IfStatement[@Else='false']
Example:
public class Foo { void bar() { if (x) { if (y) { // do stuff } } } }