Oi Leandro,

Você rodou o comando mvn compile dentro do diretório onde está o arquivo pom.xml? Qual foi o resultado mostrado no terminal depois do comando?

leandro@leandro-Z270X-Gaming-K5:~/workspace/produtos$ mvn compile
WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by com.google.inject.internal.cglib.core.$ReflectUtils$1 (file:/usr/share/maven/lib/guice.jar) to method java.lang.ClassLoader.defineClass(java.lang.String,byte[],int,int,java.security.ProtectionDomain)
WARNING: Please consider reporting this to the maintainers of com.google.inject.internal.cglib.core.$ReflectUtils$1
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release
[INFO] Scanning for projects...
[INFO] 
[INFO] ------------------------------------------------------------------------
[INFO] Building produtos 1.0-SNAPSHOT
[INFO] ------------------------------------------------------------------------
Downloading from central: https://repo.maven.apache.org/maven2/javax/inject/javax.inject/1/javax.inject-1.pom
Downloaded from central: https://repo.maven.apache.org/maven2/javax/inject/javax.inject/1/javax.inject-1.pom (612 B at 544 B/s)
Downloading from central: https://repo.maven.apache.org/maven2/javax/inject/javax.inject/1/javax.inject-1.jar
Downloaded from central: https://repo.maven.apache.org/maven2/javax/inject/javax.inject/1/javax.inject-1.jar (2.5 kB at 8.5 kB/s)
[INFO] 
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ produtos ---
[WARNING] Using platform encoding (UTF-8 actually) to copy filtered resources, i.e. build is platform dependent!
[INFO] skip non existing resourceDirectory /home/leandro/workspace/produtos/src/main/resources
[INFO] 
[INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ produtos ---
[INFO] Changes detected - recompiling the module!
[WARNING] File encoding has not been set, using platform encoding UTF-8, i.e. build is platform dependent!
[INFO] Compiling 2 source files to /home/leandro/workspace/produtos/target/classes
[INFO] -------------------------------------------------------------
[ERROR] COMPILATION ERROR : 
[INFO] -------------------------------------------------------------
[ERROR] Source option 5 is no longer supported. Use 6 or later.
[ERROR] Target option 1.5 is no longer supported. Use 1.6 or later.
[INFO] 2 errors 
[INFO] -------------------------------------------------------------
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 2.769 s
[INFO] Finished at: 2019-02-18T20:28:15-03:00
[INFO] Final Memory: 13M/50M
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.1:compile (default-compile) on project produtos: Compilation failure: Compilation failure: 
[ERROR] Source option 5 is no longer supported. Use 6 or later.
[ERROR] Target option 1.5 is no longer supported. Use 1.6 or later.
[ERROR] -> [Help 1]
[ERROR] 
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR] 
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoFailureException
leandro@leandro-Z270X-Gaming-K5:~/workspace/produtos$ 

leandro@leandro-Z270X-Gaming-K5:~/workspace/produtos$ ls pom.xml src target

Fala Leandro,

Tente colocar essa tag de propriedade dentro da tag project no pom.xml:

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

E a configuração de build, também dentro da tag project:

<build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.8.0</version>
        <configuration>
          <source>1.8</source>
          <target>1.8</target>
        </configuration>
      </plugin>
    </plugins>
  </build>