IDEA-209947 Basic explanations for instanceof

GitOrigin-RevId: 86697e1b8f0a1d905c8b17b732bb01f045e4d4b6

java/java-tests/testData/inspection/dataFlow/tracker/InstanceOfConflict.java

@@ -0,0 +1,14 @@
+/*
+Value is always false (s instanceof Integer)
+  Type of 's' is exactly String (s)
+    Type of 's' is known from line #10 (s instanceof String)
+ */
+import java.util.List;
+
+class Test {
+  void test(Object s) {
+    if (s instanceof String) {
+      if (<selection>s instanceof Integer</selection>) {}
+    }
+  }
+}

java/java-tests/testData/inspection/dataFlow/tracker/InstanceOfNull.java

@@ -0,0 +1,12 @@
+/*
+Value is always false (s instanceof String)
+  Value 's' is always 'null' (s)
+    's == null' was established from condition (s == null)
+ */
+import java.util.List;
+
+class Test {
+  void test(Object s) {
+    if (s == null && <selection>s instanceof String</selection>) {}
+  }
+}

java/java-tests/testData/inspection/dataFlow/tracker/InstanceOfRedundant.java

@@ -0,0 +1,14 @@
+/*
+Value is always true (s instanceof CharSequence)
+  Type of 's' is exactly String (s)
+    Type of 's' is known from line #10 (s instanceof String)
+ */
+import java.util.List;
+
+class Test {
+  void test(Object s) {
+    if (s instanceof String) {
+      if (<selection>s instanceof CharSequence</selection>) {}
+    }
+  }
+}