Maven project Error: Diamond/multicatch operator not supported in -source 1.5

I can't build my maven java web application, because of the following two errors:

diamond operator is not supported in -source 1.5
  (use -source 7 or higher to enable diamond operator)

multi-catch statement is not supported in -source 1.5
  (use -source 7 or higher to enable multi-catch statement)

I'm confused, because i use java 1.8.0 for my project, i never have actually used 1.5

What could be causing this problem and how do i solve it?

I tried to build it after adding the follwing lines in the pom.xml, but without succes:

 <properties>
        <sourceJdk>1.8</sourceJdk>
        <targetJdk>1.8</targetJdk>
 </properties>

Try declaring the maven-compiler-plugin in your pom.

           <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.1</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>