Add a comment describing SootClass name for lambdas

Author: ArsenHD

utbot-framework/src/main/kotlin/org/utbot/engine/Resolver.kt

@@ -647,7 +647,14 @@ class Resolver(
 
         val declaringClass = classLoader.loadClass(sootClass.name.substringBeforeLast("\$lambda"))
 
-        // TODO: add comments describing the format of Soot class name for lambdas, because here we transform it into the actual synthetic method name
+        // Java compiles lambdas into synthetic methods with specific names.
+        // However, Soot represents lambdas as classes.
+        // Names of these classes are the modified names of these synthetic methods.
+        // Specifically, Soot replaces some `$` signs by `_`, adds two underscores and some number
+        // to the end of the synthetic method name to form the name of a SootClass for lambda.
+        // For example, given a synthetic method `lambda$foo$1` (lambda declared in method `foo` of class `org.utbot.MyClass`),
+        // Soot will treat this lambda as a class named `org.utbot.MyClass$lambda_foo_1__5` (the last number is probably arbitrary, it's not important).
+        // Here we obtain the synthetic method name of lambda from the name of its SootClass.
         val lambdaName = sootClass.name
             .let { name ->
                 val start = name.lastIndexOf("\$lambda") + 1