unused return value inspection: method reference awareness (IDEA-134991)

java/java-tests/testData/inspection/unusedReturnValue/methodReference/expected.xml

@@ -0,0 +1,2 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<problems/>

java/java-tests/testData/inspection/unusedReturnValue/methodReference/src/B.java

@@ -0,0 +1,13 @@
+import java.util.function.Consumer;
+import java.util.function.DoubleSupplier;
+
+class B {
+
+  public void test(Consumer<DoubleSupplier> consumer) {
+    consumer.accept(this::method);
+  }
+
+  private double method() {
+    return 1;
+  }
+}