new inference: String::length should be exact (IDEA-122191)

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/newMethodRef/IDEA112191.java

@@ -0,0 +1,15 @@
+import java.util.function.ToIntFunction;
+class Test {
+  {
+    fooBar(String::length);
+  }
+
+  class Foo<K> {
+    Foo<K> then() {
+      return null;
+    }
+  }
+  static <T> Foo<T> fooBar(ToIntFunction<? super T> keyExtractor) {
+    return null;
+  }
+}