Java core fix (#383)

* Fix: Typo in aws-lambda-java-core version.

* Fix: Removing jcenter due to end of life notice.

Author: msailes

example/HelloWorldFunction/build.gradle

@@ -4,7 +4,7 @@ plugins{
 }
 
 repositories {
-    jcenter()
+    mavenCentral()
 }
 
 dependencies {
@@ -26,7 +26,7 @@ dependencies {
     implementation 'software.amazon.lambda:powertools-validation:1.5.0'
     aspectpath 'software.amazon.lambda:powertools-validation:1.5.0'
 
-    implementation 'com.amazonaws:aws-lambda-java-core:1.5.0'
+    implementation 'com.amazonaws:aws-lambda-java-core:1.2.1'
     implementation 'com.amazonaws:aws-lambda-java-events:3.1.0'
 
     implementation 'org.apache.logging.log4j:log4j-api:2.13.3'

example/HelloWorldFunction/pom.xml

@@ -46,7 +46,7 @@
         <dependency>
             <groupId>com.amazonaws</groupId>
             <artifactId>aws-lambda-java-core</artifactId>
-            <version>1.5.0</version>
+            <version>1.2.1</version>
         </dependency>
         <dependency>
             <groupId>com.amazonaws</groupId>