Update sendgrid-java dependency minimum version to 4.4.0

- some class not found since sendgrid-java version 4.4.0
- see sendgrid/sendgrid-java#306

Author: akunzai

build.gradle

@@ -15,11 +15,11 @@ repositories {
 }
 
 dependencies {
-    implementation "com.sendgrid:sendgrid-java:4.0.0"
+    implementation "com.sendgrid:sendgrid-java:4.4.0"
     implementation "com.sun.mail:javax.mail:1.5.0"
     implementation "org.apache.logging.log4j:log4j-core:2.9.0"
     annotationProcessor "org.apache.logging.log4j:log4j-core:2.9.0"
-    testImplementation "com.sendgrid:sendgrid-java:4.3.0"
+    testImplementation "com.sendgrid:sendgrid-java:4.6.8"
     testImplementation "junit:junit:4.12"
 }
 

src/main/java/com/github/akunzai/log4j/SendGridManager.java

@@ -1,6 +1,8 @@
 package com.github.akunzai.log4j;
 
 import com.sendgrid.*;
+import com.sendgrid.helpers.mail.Mail;
+import com.sendgrid.helpers.mail.objects.Content;
 import org.apache.logging.log4j.LoggingException;
 import org.apache.logging.log4j.core.Layout;
 import org.apache.logging.log4j.core.LogEvent;

src/main/java/com/github/akunzai/log4j/SendGridMessageBuilder.java

@@ -1,8 +1,8 @@
 package com.github.akunzai.log4j;
 
-import com.sendgrid.Email;
-import com.sendgrid.Mail;
-import com.sendgrid.Personalization;
+import com.sendgrid.helpers.mail.Mail;
+import com.sendgrid.helpers.mail.objects.Email;
+import com.sendgrid.helpers.mail.objects.Personalization;
 import org.apache.logging.log4j.core.util.Builder;
 
 import javax.mail.Message;

src/test/java/com/github/akunzai/log4j/SendGridAppenderTest.java

@@ -1,9 +1,9 @@
 package com.github.akunzai.log4j;
 
 import com.fasterxml.jackson.databind.ObjectMapper;
-import com.sendgrid.Content;
-import com.sendgrid.Mail;
-import com.sendgrid.Personalization;
+import com.sendgrid.helpers.mail.Mail;
+import com.sendgrid.helpers.mail.objects.Content;
+import com.sendgrid.helpers.mail.objects.Personalization;
 import org.apache.logging.log4j.Level;
 import org.apache.logging.log4j.ThreadContext;
 import org.apache.logging.log4j.core.Logger;