Add tests for KT-19511 and KT-21192 (with void -> boolean)

idea/testData/inspections/unusedEquals/consumer/Consumer.java

@@ -0,0 +1,5 @@
+package consumer;
+
+public interface Consumer<T> {
+    boolean consumer(T t);
+}

idea/testData/inspections/unusedEquals/test.kt

@@ -61,4 +61,19 @@ fun foo8(a: Int) {
     if (a > 1) a == 10 else a == -1 // both unused
 
     if (a == 10) {} else if (a == -1) {} // both used
+}
+
+fun foo9() {
+    consumer.Consumer<Any?> { it == null } // used
+}
+
+class Test(val successCondition: (Int) -> Boolean) {
+    fun pass(num: Int): Boolean = successCondition(num)
+}
+
+fun foo10() {
+    val t1 = Test({it == 69})
+    if (t1.pass(42)) {
+        //
+    }
 }