diff --git a/core-java/pom.xml b/core-java/pom.xml
index cce714451e..cad458596b 100644
--- a/core-java/pom.xml
+++ b/core-java/pom.xml
@@ -10,8 +10,8 @@
     <parent>
         <groupId>com.baeldung</groupId>
         <artifactId>parent-java</artifactId>
-    	<version>0.0.1-SNAPSHOT</version>
-    	<relativePath>../parent-java</relativePath>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../parent-java</relativePath>
     </parent>
 
     <dependencies>
@@ -197,12 +197,7 @@
             <groupId>javax.mail</groupId>
             <artifactId>mail</artifactId>
             <version>${javax.mail.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>javax.mail</groupId>
-            <artifactId>mail</artifactId>
-            <version>1.5.0-b01</version>
-        </dependency>
+      </dependency>
         <dependency>
             <groupId>com.ibm.icu</groupId>
             <artifactId>icu4j</artifactId>
@@ -255,6 +250,7 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-jar-plugin</artifactId>
+                <version>${maven-jar-plugin.version}</version>
                 <configuration>
                     <archive>
                         <manifest>
@@ -293,6 +289,7 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-shade-plugin</artifactId>
+                <version>${maven-shade-plugin.version}</version>
                 <executions>
                     <execution>
                         <goals>
@@ -314,6 +311,7 @@
             <plugin>
                 <groupId>com.jolira</groupId>
                 <artifactId>onejar-maven-plugin</artifactId>
+                <version>${onejar-maven-plugin.version}</version>
                 <executions>
                     <execution>
                         <configuration>
@@ -331,6 +329,7 @@
             <plugin>
                 <groupId>org.springframework.boot</groupId>
                 <artifactId>spring-boot-maven-plugin</artifactId>
+                <version>${spring-boot-maven-plugin.version}</version>
                 <executions>
                     <execution>
                         <goals>
@@ -478,6 +477,10 @@
         <maven-javadoc-plugin.version>3.0.0-M1</maven-javadoc-plugin.version>
         <exec-maven-plugin.version>1.6.0</exec-maven-plugin.version>
         <javax.mail.version>1.5.0-b01</javax.mail.version>
+        <maven-jar-plugin.version>3.0.2</maven-jar-plugin.version>
+        <onejar-maven-plugin.version>1.4.4</onejar-maven-plugin.version>
+        <maven-shade-plugin.version>3.1.1</maven-shade-plugin.version>
+        <spring-boot-maven-plugin.version>2.0.3.RELEASE</spring-boot-maven-plugin.version>
         <icu4j.version>61.1</icu4j.version>
     </properties>
 
diff --git a/core-java/src/main/java/com/baeldung/customexception/FileManager.java b/core-java/src/main/java/com/baeldung/customexception/FileManager.java
new file mode 100644
index 0000000000..b6f4d960aa
--- /dev/null
+++ b/core-java/src/main/java/com/baeldung/customexception/FileManager.java
@@ -0,0 +1,43 @@
+package com.baeldung.customexception;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.util.Scanner;
+
+public class FileManager {
+
+    public static String getFirstLine(String fileName) throws IncorrectFileNameException {
+        try (Scanner file = new Scanner(new File(fileName))) {
+            if (file.hasNextLine()) {
+                return file.nextLine();
+            } else {
+                throw new IllegalArgumentException("Non readable file");
+            }
+        } catch (FileNotFoundException err) {
+            if (!isCorrectFileName(fileName)) {
+                throw new IncorrectFileNameException("Incorrect filename : " + fileName, err);
+            }
+            // Logging etc
+        } catch (IllegalArgumentException err) {
+            if (!containsExtension(fileName)) {
+                throw new IncorrectFileExtensionException("Filename does not contain extension : " + fileName, err);
+            }
+            // Other error cases and logging
+        }
+        return "Default First Line";
+    }
+
+    private static boolean containsExtension(String fileName) {
+        if (fileName.contains(".txt") || fileName.contains(".doc"))
+            return true;
+        return false;
+    }
+
+    private static boolean isCorrectFileName(String fileName) {
+        if (fileName.equals("wrongFileName.txt"))
+            return false;
+        else
+            return true;
+    }
+
+}
diff --git a/core-java/src/main/java/com/baeldung/customexception/IncorrectFileExtensionException.java b/core-java/src/main/java/com/baeldung/customexception/IncorrectFileExtensionException.java
new file mode 100644
index 0000000000..c6dc6d6964
--- /dev/null
+++ b/core-java/src/main/java/com/baeldung/customexception/IncorrectFileExtensionException.java
@@ -0,0 +1,9 @@
+package com.baeldung.customexception;
+
+public class IncorrectFileExtensionException extends RuntimeException{
+    private static final long serialVersionUID = 1L;
+
+    public IncorrectFileExtensionException(String errorMessage, Throwable err) {
+        super(errorMessage, err);
+    }
+}
diff --git a/core-java/src/main/java/com/baeldung/customexception/IncorrectFileNameException.java b/core-java/src/main/java/com/baeldung/customexception/IncorrectFileNameException.java
new file mode 100644
index 0000000000..a804cadb84
--- /dev/null
+++ b/core-java/src/main/java/com/baeldung/customexception/IncorrectFileNameException.java
@@ -0,0 +1,9 @@
+package com.baeldung.customexception;
+
+public class IncorrectFileNameException extends Exception {
+    private static final long serialVersionUID = 1L;
+    
+    public IncorrectFileNameException(String errorMessage, Throwable err) {
+        super(errorMessage, err);
+    }
+}
diff --git a/core-java/src/test/java/com/baeldung/customexception/IncorrectFileExtensionExceptionUnitTest.java b/core-java/src/test/java/com/baeldung/customexception/IncorrectFileExtensionExceptionUnitTest.java
new file mode 100644
index 0000000000..230698f719
--- /dev/null
+++ b/core-java/src/test/java/com/baeldung/customexception/IncorrectFileExtensionExceptionUnitTest.java
@@ -0,0 +1,29 @@
+package com.baeldung.customexception;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.io.File;
+
+import org.junit.Test;
+
+public class IncorrectFileExtensionExceptionUnitTest {
+
+    @Test
+    public void testWhenCorrectFileExtensionGiven_ReceivesNoException() throws IncorrectFileNameException {
+        assertThat(FileManager.getFirstLine("correctFileNameWithProperExtension.txt")).isEqualTo("Default First Line");
+    }
+
+    @Test(expected = IncorrectFileExtensionException.class)
+    public void testWhenCorrectFileNameExceptionThrown_ReceivesNoException() throws IncorrectFileNameException {
+        StringBuffer sBuffer = new StringBuffer();
+        sBuffer.append("src");
+        sBuffer.append(File.separator);
+        sBuffer.append("test");
+        sBuffer.append(File.separator);
+        sBuffer.append("resources");
+        sBuffer.append(File.separator);
+        sBuffer.append("correctFileNameWithoutProperExtension");
+        FileManager.getFirstLine(sBuffer.toString());
+    }
+
+}
diff --git a/core-java/src/test/java/com/baeldung/customexception/IncorrectFileNameExceptionUnitTest.java b/core-java/src/test/java/com/baeldung/customexception/IncorrectFileNameExceptionUnitTest.java
new file mode 100644
index 0000000000..acb05eb763
--- /dev/null
+++ b/core-java/src/test/java/com/baeldung/customexception/IncorrectFileNameExceptionUnitTest.java
@@ -0,0 +1,19 @@
+package com.baeldung.customexception;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.Test;
+
+public class IncorrectFileNameExceptionUnitTest {
+
+    @Test(expected = IncorrectFileNameException.class)
+    public void testWhenIncorrectFileNameExceptionThrown_ReceivesIncorrectFileNameException() throws IncorrectFileNameException {
+        FileManager.getFirstLine("wrongFileName.txt");
+    }
+
+    @Test
+    public void testWhenCorrectFileNameExceptionThrown_ReceivesNoException() throws IncorrectFileNameException {
+        assertThat(FileManager.getFirstLine("correctFileName.txt")).isEqualTo("Default First Line");
+    }
+
+}
diff --git a/core-java/src/test/resources/correctFileNameWithoutProperExtension b/core-java/src/test/resources/correctFileNameWithoutProperExtension
new file mode 100644
index 0000000000..e69de29bb2