don't throw exceptions on contracts with several clauses

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

@@ -0,0 +1,13 @@
+import org.jetbrains.annotations.Contract;
+
+public class Foo {
+
+    String foo(Object escaper, String s) {
+        return escapeStr(s, escaper);
+    }
+
+    @Contract("null,_->null;!null,_->!null")
+    String escapeStr(String s, Object o) {
+        return s;
+    }
+}