dfa: understand assertThat notnull (IDEA-125977, IDEA-65004)

java/java-tests/testData/inspection/dataFlow/fixture/AssertThat.java

@@ -0,0 +1,18 @@
+import org.hamcrest.CoreMatchers;
+import org.jetbrains.annotations.Nullable;
+import static org.hamcrest.CoreMatchers.*;
+import static org.junit.Assert.assertThat;
+
+class Contracts {
+
+  private void checkNotNullValue(@Nullable Object o) {
+    assertThat(o, CoreMatchers.<Object>notNullValue());
+    System.out.println(o.hashCode());
+  }
+
+  private void checkNotEqualToNull(@Nullable String test) {
+    assertThat("String is null", test, not(equalTo(null)));
+    int length = test.length();
+  }
+
+}