fix all the checkstyle violations (iluwatar#79)

Author: sergejsvisockis

active-record/src/main/java/com/iluwatar/activerecord/App.java

@@ -5,6 +5,9 @@
 import lombok.extern.slf4j.Slf4j;
 import org.h2.jdbcx.JdbcDataSource;
 
+/**
+ * The amin application for the manual testing purposes.
+ */
 @Slf4j
 public class App {
 
@@ -28,7 +31,12 @@ public class App {
       + "    CONSTRAINT customer_id_fk FOREIGN KEY (customer_id) REFERENCES customer (id)\n"
       + ")";
 
-
+  /**
+   * Java main method to execute all the logic out there.
+   *
+   * @param args arguments.
+   * @throws Exception Any sort of exception that have to be picked up by the JVM.
+   */
   public static void main(final String[] args) throws Exception {
     final var dataSource = createDataSource();
     createSchema(dataSource);
@@ -48,7 +56,7 @@ private static void executeOperation() {
     order.setId(1L);
     order.setOrderNumber("O123");
 
-//    customer.addOrder(order);
+    // customer.addOrder(order);
     customer.save();
 
     LOGGER.info("The customer data by ID={}", customer.findById(1L));

active-record/src/main/java/com/iluwatar/activerecord/Customer.java

@@ -8,6 +8,9 @@
 import lombok.Setter;
 import lombok.ToString;
 
+/**
+ * The customer domain model.
+ */
 @Getter
 @Setter
 @ToString

active-record/src/main/java/com/iluwatar/activerecord/Order.java

@@ -6,6 +6,9 @@
 import lombok.NoArgsConstructor;
 import lombok.Setter;
 
+/**
+ * An order domain model.
+ */
 @Getter
 @Setter
 @EqualsAndHashCode(onlyExplicitlyIncluded = true)

active-record/src/main/java/com/iluwatar/activerecord/RecordBase.java

@@ -11,6 +11,11 @@
 import lombok.RequiredArgsConstructor;
 import lombok.Setter;
 
+/**
+ * An active record base supposed to hold all the necessary active record pattern logic.
+ *
+ * @param <T> an active record type.
+ */
 @RequiredArgsConstructor
 public abstract class RecordBase<T extends RecordBase<?>> {
 
@@ -117,8 +122,10 @@ private String constructFindByIdQuery() {
   private T getDeclaredClassInstance() {
     try {
       return clazz.getDeclaredConstructor().newInstance();
-    } catch (InvocationTargetException | NoSuchMethodException | IllegalAccessException |
-             InstantiationException e) {
+    } catch (InvocationTargetException
+             | NoSuchMethodException
+             | IllegalAccessException
+             | InstantiationException e) {
       throw new IllegalStateException(
           "Unable to create a new instance of the class=" + clazz.getName(), e);
     }