[java][tests] Fix/suppress unchecked warnings

Summary:
`make test` failed in some test directories, because we were getting warnings
 ```
Foo.java uses unchecked or unsafe operations.
```

This diff fixes or suppresses these warnings.

Reviewed By: skcho

Differential Revision: D20557572

fbshipit-source-id: 63ecd3dfa

infer/tests/codetoanalyze/java/impurity/PurityModeled.java

@@ -131,6 +131,7 @@ class PurityModeled {
     for (Color c : Color.values()) {}
   }
 
+  @SuppressWarnings("unchecked")
   void clone_pure(ArrayList<String> list) {
     ArrayList<String> cloned = (ArrayList<String>) list.clone();
     cloned.add(""); // no change the list

infer/tests/codetoanalyze/java/performance/ArrayListTest.java

@@ -294,7 +294,7 @@ public class ArrayListTest {
     }
   }
 
-  ArrayList<Elt> arr = new ArrayList();
+  ArrayList<Elt> arr = new ArrayList<Elt>();
 
   void boolean_control_var_linear() {
     for (int i = 0; i < arr.size(); i++) {

infer/tests/codetoanalyze/java/purity/PurityModeled.java

@@ -28,6 +28,7 @@ class PurityModeled {
     for (Color c : Color.values()) {}
   }
 
+  @SuppressWarnings("unchecked")
   void clone_pure(ArrayList<String> list) {
     ArrayList<String> cloned = (ArrayList<String>) list.clone();
     cloned.add(""); // no change the list