import org.apache.commons.io.FileUtils;
import org.gradle.workers.WorkAction;

import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;

public abstract class GenerateMD5 implements WorkAction<MD5WorkParameters> { // <1>
    @Override
    public void execute() {
        try {
            File sourceFile = getParameters().getSourceFile().getAsFile().get();

import org.apache.commons.io.FileUtils;
import org.gradle.workers.WorkAction;

import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;

public abstract class GenerateMD5 implements WorkAction<MD5WorkParameters> {
    @Override
    public void execute() {
        try {
            File sourceFile = getParameters().getSourceFile().getAsFile().get();
            File md5File = getParameters().getMD5File().getAsFile().get();

There is no need to create a concrete implementation because Gradle will generate one for us at runtime.

.buildSrc/src/main/java/MD5WorkParameters.java
[source,java]
----
include::{snippetsPath}/workerApi/md5NoIsolation/groovy/buildSrc/src/main/java/MD5WorkParameters.java[]
----
<1> Use `Property` objects to represent the source and MD5 hash files.