extract contract checking to a separatate inspection

java/java-tests/testData/inspection/dataFlow/contractCheck/SignatureIssues.java

@@ -0,0 +1,14 @@
+import org.jetbrains.annotations.Contract;
+import org.jetbrains.annotations.Nullable;
+
+class Foo {
+  @Contract(<warning descr="A contract clause must be in form arg1, ..., argN -> return-value">"a"</warning>)
+  void malformedContract() {}
+
+  @Contract(<warning descr="Method takes 2 parameters, while contract clause number 1 expects 1">"null -> _"</warning>)
+  void wrongParameterCount(Object a, boolean b) {}
+
+  @Contract(pure=<warning descr="Pure methods must return something, void is not allowed as a return type">true</warning>)
+  void voidPureMethod() {}
+
+}