Check out example codes for "maven compiler plugin for java 13". It will help you in understanding the concepts better.

Code Example 1

<properties>    <maven.compiler.target>1.8</maven.compiler.target>    <maven.compiler.source>1.8</maven.compiler.source></properties>

Code Example 2

<project>
...
 <properties>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
  </properties>
...
</project>

Code Example 3

<plugin>
	<groupId>org.apache.maven.plugins</groupId>
	<artifactId>maven-compiler-plugin</artifactId>
	<version>3.8.0</version>
	<configuration>
		<release>13</release>
		<compilerArgs>
			--enable-preview
		</compilerArgs>
	</configuration>
</plugin>

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