Adding Reflections files (#6393)

* Adding Reflections dependency

* Adding Reflections java class

* Adding Reflections UT

libraries/src/main/java/com/baeldung/reflections/ReflectionsApp.java

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+package com.baeldung.reflections;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.Method;
+import java.util.Date;
+import java.util.Set;
+import java.util.regex.Pattern;
+
+import org.reflections.Reflections;
+import org.reflections.scanners.MethodAnnotationsScanner;
+import org.reflections.scanners.MethodParameterScanner;
+import org.reflections.scanners.ResourcesScanner;
+import org.reflections.scanners.Scanner;
+import org.reflections.scanners.SubTypesScanner;
+import org.reflections.util.ClasspathHelper;
+import org.reflections.util.ConfigurationBuilder;
+
+public class ReflectionsApp {
+
+    public Set<Class<? extends Scanner>> getReflectionsSubTypes() {
+        Reflections reflections = new Reflections("org.reflections");
+        Set<Class<? extends Scanner>> scannersSet = reflections.getSubTypesOf(Scanner.class);
+        return scannersSet;
+    }
+
+    public Set<Class<?>> getJDKFunctinalInterfaces() {
+        Reflections reflections = new Reflections("java.util.function");
+        Set<Class<?>> typesSet = reflections.getTypesAnnotatedWith(FunctionalInterface.class);
+        return typesSet;
+    }
+
+    public Set<Method> getDateDeprecatedMethods() {
+        Reflections reflections = new Reflections(java.util.Date.class, new MethodAnnotationsScanner());
+        Set<Method> deprecatedMethodsSet = reflections.getMethodsAnnotatedWith(Deprecated.class);
+        return deprecatedMethodsSet;
+    }
+
+    @SuppressWarnings("rawtypes")
+    public Set<Constructor> getDateDeprecatedConstructors() {
+        Reflections reflections = new Reflections(java.util.Date.class, new MethodAnnotationsScanner());
+        Set<Constructor> constructorsSet = reflections.getConstructorsAnnotatedWith(Deprecated.class);
+        return constructorsSet;
+    }
+
+    public Set<Method> getMethodsWithDateParam() {
+        Reflections reflections = new Reflections(java.text.SimpleDateFormat.class, new MethodParameterScanner());
+        Set<Method> methodsSet = reflections.getMethodsMatchParams(Date.class);
+        return methodsSet;
+    }
+
+    public Set<Method> getMethodsWithVoidReturn() {
+        Reflections reflections = new Reflections(java.text.SimpleDateFormat.class, new MethodParameterScanner());
+        Set<Method> methodsSet = reflections.getMethodsReturn(void.class);
+        return methodsSet;
+    }
+
+    public Set<String> getPomXmlPaths() {
+        Reflections reflections = new Reflections(new ResourcesScanner());
+        Set<String> resourcesSet = reflections.getResources(Pattern.compile(".*pom\\.xml"));
+        return resourcesSet;
+    }
+
+    public Set<Class<? extends Scanner>> getReflectionsSubTypesUsingBuilder() {
+        Reflections reflections = new Reflections(new ConfigurationBuilder().setUrls(ClasspathHelper.forPackage("org.reflections"))
+            .setScanners(new SubTypesScanner()));
+
+        Set<Class<? extends Scanner>> scannersSet = reflections.getSubTypesOf(Scanner.class);
+        return scannersSet;
+    }
+
+}

libraries/src/test/java/com/baeldung/reflections/ReflectionsUnitTest.java

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+package com.baeldung.reflections;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+
+import org.junit.jupiter.api.Test;
+
+public class ReflectionsUnitTest {
+
+    @Test
+    public void givenTypeThenGetAllSubTypes() {
+        ReflectionsApp reflectionsApp = new ReflectionsApp();
+        assertFalse(reflectionsApp.getReflectionsSubTypes()
+            .isEmpty());
+    }
+
+    @Test
+    public void givenTypeAndUsingBuilderThenGetAllSubTypes() {
+        ReflectionsApp reflectionsApp = new ReflectionsApp();
+        assertFalse(reflectionsApp.getReflectionsSubTypesUsingBuilder()
+            .isEmpty());
+    }
+
+    @Test
+    public void givenAnnotationThenGetAllAnnotatedMethods() {
+        ReflectionsApp reflectionsApp = new ReflectionsApp();
+        assertFalse(reflectionsApp.getDateDeprecatedMethods()
+            .isEmpty());
+    }
+
+    @Test
+    public void givenAnnotationThenGetAllAnnotatedConstructors() {
+        ReflectionsApp reflectionsApp = new ReflectionsApp();
+        assertFalse(reflectionsApp.getDateDeprecatedConstructors()
+            .isEmpty());
+    }
+
+    @Test
+    public void givenParamTypeThenGetAllMethods() {
+        ReflectionsApp reflectionsApp = new ReflectionsApp();
+        assertFalse(reflectionsApp.getMethodsWithDateParam()
+            .isEmpty());
+    }
+
+    @Test
+    public void givenReturnTypeThenGetAllMethods() {
+        ReflectionsApp reflectionsApp = new ReflectionsApp();
+        assertFalse(reflectionsApp.getMethodsWithVoidReturn()
+            .isEmpty());
+    }
+}