VarInt: implement equals() and hashCode()

`originallyEncodedSize` is not considered on purpose, because it is only
relevant for serialization.

core/src/main/java/org/bitcoinj/base/VarInt.java

@@ -21,6 +21,7 @@ import java.nio.BufferOverflowException;
 import java.nio.BufferUnderflowException;
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
+import java.util.Objects;
 
 import static org.bitcoinj.base.internal.Preconditions.check;
 
@@ -177,4 +178,17 @@ public class VarInt {
         }
         return buf;
     }
+
+    @Override
+    public boolean equals(Object o) {
+        // originallyEncodedSize is not considered on purpose
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        return value == ((VarInt) o).value;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(value);
+    }
 }