
Previously, the custom layout sample did not configure the source and target for the compiler. This meant that both defaulted to 1.5 which is not supported by Java 9's javac. The oldest support version is 1.6. This commit sets the maven.compiler.source and maven.compiler.target properties to 1.8 (the lowest version support by Boot 2.0) allowing the sample to build with both Java 8 and Java 9. See gh-10515