Define a variable and set it to a default value if something goes wrong during definition
All you need is some regular Java/Groovy code:
def jenkinsBuild = System.getenv("BUILD_NUMBER") ?: "0"
The code above uses Groovy's "elvis" operator, and is a shorthand for the following code, which uses Java's ternary operator:
def buildNumber = System.getenv("BUILD_NUMBER")
def jenkinsBuild = buildNumber != null ? buildNumber : "0"
Here's the answer to using a Java plain object (JDK8):
public class Sample {
private String region;
private String fruit;
public Sample() {
region = System.getenv().getOrDefault("REGION", null);
fruit = System.getenv().getOrDefault("FRUIT", "apple");
}
}