Upgrade to SendGrid 4.4.4

Closes gh-20092

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/sendgrid/SendGridAutoConfigurationTests.java

 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -52,7 +52,7 @@ class SendGridAutoConfigurationTests {
 	void expectedSendGridBeanCreatedApiKey() {
 		loadContext("spring.sendgrid.api-key:SG.SECRET-API-KEY");
 		SendGrid sendGrid = this.context.getBean(SendGrid.class);
-		assertThat(sendGrid).extracting("apiKey").isEqualTo("SG.SECRET-API-KEY");
+		assertThat(sendGrid.getRequestHeaders().get("Authorization")).isEqualTo("Bearer SG.SECRET-API-KEY");
 	}
 
 	@Test
@@ -66,7 +66,7 @@ class SendGridAutoConfigurationTests {
 	void autoConfigurationNotFiredWhenBeanAlreadyCreated() {
 		loadContext(ManualSendGridConfiguration.class, "spring.sendgrid.api-key:SG.SECRET-API-KEY");
 		SendGrid sendGrid = this.context.getBean(SendGrid.class);
-		assertThat(sendGrid).extracting("apiKey").isEqualTo("SG.CUSTOM_API_KEY");
+		assertThat(sendGrid.getRequestHeaders().get("Authorization")).isEqualTo("Bearer SG.CUSTOM_API_KEY");
 	}
 
 	@Test

spring-boot-project/spring-boot-dependencies/build.gradle

@@ -1533,7 +1533,7 @@ bom {
 			]
 		}
 	}
-	library("SendGrid", "4.4.1") {
+	library("SendGrid", "4.4.4") {
 		group("com.sendgrid") {
 			modules = [
 				"sendgrid-java"