The JDK 7 compiler seems to accept (with warning) a strange construction that earlier versions of the compiler reject (albeit with an odd error message).

$ cat StrangeGenerics.java
import java.util.ArrayList;
import java.util.List;
class StrangeGenerics {
    void m() {
        List<String> x = new <String>ArrayList();
    }
}
$ /space/jdk5/bin/javac -J-showversion -d /tmp -Xlint -source 1.5 StrangeGenerics.java
java version "1.5.0_15"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_15-b04)
Java HotSpot(TM) Server VM (build 1.5.0_15-b04, mixed mode)

StrangeGenerics.java:5: cannot find symbol
symbol : constructor <java.lang.String>ArrayList()
location: class java.util.ArrayList
        List<String> x = new <String>ArrayList();
                         ^
1 error
$ /space/jdk6/bin/javac -J-showversion -d /tmp -Xlint -source 1.5 StrangeGenerics.java
java version "1.6.0_11"
Java(TM) SE Runtime Environment (build 1.6.0_11-b03)
Java HotSpot(TM) Client VM (build 11.0-b16, mixed mode, sharing)

StrangeGenerics.java:5: cannot find symbol
symbol : constructor <java.lang.String>ArrayList()
location: class java.util.ArrayList
        List<String> x = new <String>ArrayList();
                         ^
1 error
$ /space/jdk7/bin/javac -J-showversion -d /tmp -Xlint -source 1.5 StrangeGenerics.java
java version "1.7.0-ea"
Java(TM) SE Runtime Environment (build 1.7.0-ea-b43)
Java HotSpot(TM) Client VM (build 14.0-b10, mixed mode, sharing)

StrangeGenerics.java:5: warning: [rawtypes] found raw type: java.util.ArrayList
missing type parameters for generic class java.util.ArrayList<E>
        List<String> x = new <String>ArrayList();
                                     ^
StrangeGenerics.java:5: warning: [unchecked] unchecked conversion
found : java.util.ArrayList
required: java.util.List<java.lang.String>
        List<String> x = new <String>ArrayList();
                         ^
2 warnings