add PasswordValidator class with validate method

src/main/java/PasswordValidator.java

@@ -0,0 +1,6 @@
+public class PasswordValidator {
+
+    public boolean validate(String password) {
+        return false;
+    }
+}

src/test/java/PasswordValidatorTest.java

@@ -0,0 +1,12 @@
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class PasswordValidatorTest {
+
+    @Test
+    void validate() {
+        PasswordValidator passwordValidator = new PasswordValidator();
+        assertFalse(passwordValidator.validate(""));
+    }
+}