Revert "bump Java Language Level up to 16"

This reverts commit 464c2b0.

Author: Ghost-chu

pom.xml

@@ -103,16 +103,11 @@
                 <artifactId>maven-compiler-plugin</artifactId>
                 <version>3.8.1</version>
                 <configuration>
-                    <release>8</release>
-                    <source>16</source>
-                    <target>16</target>
+                    <source>1.8</source>
+                    <target>1.8</target>
                     <encoding>UTF-8</encoding>
                     <!--Use this comments args when compiler is NullPointerException-->
                     <!--<forceJavacCompilerUse>true</forceJavacCompilerUse>-->
-                    <compilerArgs>
-                        <arg>-Xplugin:jabel</arg>
-                        <arg>--enable-preview</arg>
-                    </compilerArgs>
                 </configuration>
             </plugin>
             <plugin>
@@ -953,11 +948,5 @@
             <systemPath>${project.basedir}/lib/IridiumSkyblock-3.1.1.jar</systemPath>
             <scope>system</scope>
         </dependency>
-        <dependency>
-            <groupId>com.github.bsideup.jabel</groupId>
-            <artifactId>jabel-javac-plugin</artifactId>
-            <version>0.4.1</version>
-            <scope>provided</scope>
-        </dependency>
     </dependencies>
 </project>