There is a library that provides a better ProcessBuilder, zt-exec. This library can do exactly what you are asking for and more.
Here's what your code would look like with zt-exec instead of ProcessBuilder :
add the dependency :
<dependency>
<groupId>org.zeroturnaround</groupId>
<artifactId>zt-exec</artifactId>
<version>1.11</version>
</dependency>
The code :
new ProcessExecutor()
.command("somecommand", "arg1", "arg2")
.redirectOutput(System.out)
.redirectError(System.err)
.execute();
Documentation of the library is here : https://github.com/zeroturnaround/zt-exec/