feat: Demonstrate method overloading with sum() and fun() methods

WHAT the code does:
- Defines a class `Overloading` to showcase Java method overloading.
- `sum(int, int)` → adds two integers.
- `sum(int, int, int)` → adds three integers.
- `fun(int)` → prints a message and integer value.
- `fun(String)` → prints a message and string value.
- `main()` calls both `fun()` versions and the overloaded `sum()`.

WHY this matters:
- Demonstrates **compile-time polymorphism** (method overloading) in Java.
- Shows how the compiler selects the correct method based on argument type and count.
- Useful for creating cleaner APIs with multiple input variations.

HOW it works:
1. `fun(7)` → calls `fun(int)` → prints "first one" and `7`.
2. `fun("Somesh Diwan")` → calls `fun(String)` → prints "Second one" and name.
3. `sum(3, 4, 78)` → calls `sum(int, int, int)` → returns `85`, printed to console.

Tips & gotchas:
- Overloading depends on **method signature** (name + parameter list).
- Return type alone cannot differentiate overloaded methods.
- Ambiguity can occur if compiler cannot resolve best match (e.g., `fun(null)` matches both `fun(String)` and `fun(Object)` if defined).
- For readability, ensure overloaded methods logically relate (like multiple `sum` variations).

Use-cases:
- Calculator utilities with variable argument counts.
- Logging methods accepting different data types.
- Educational examples to understand **polymorphism**.
- Cleaner APIs by avoiding multiple method names for similar tasks.

Short key: class-overloading-sum-fun-demo.

Signed-off-by: https://github.com/Someshdiwan <someshdiwan369@gmail.com>

Author: Someshdiwan

Section10Methods/Methods 2.O/src/Overloading.java

@@ -1,15 +1,18 @@
 public class Overloading {
     public static void main(String[] args) {
-//        fun(67);
-//        fun("Kunal Kushwaha");
-        int ans = sum(3, 4, 78);
-        System.out.println(ans);
+          fun(7);
+          fun("Somesh Diwan");
+
+          int ans = sum(3, 4, 78);
+          System.out.println(ans);
     }
 
+    //First method called.
     static int sum(int a, int b) {
         return a + b;
     }
 
+    //Second method called.
     static int sum(int a, int b, int c) {
         return a + b + c;
     }