Allowing empty valued global variables in config file

integrations/src/test/resources/io/jenkins/plugins/casc/GlobalNodePropertiesTest.yml

@@ -4,3 +4,5 @@ jenkins:
         env:
           - key: FOO
             value: BAR
+          - key: FOO2
+            value: ""

plugin/src/main/java/io/jenkins/plugins/casc/core/GlobalNodePropertiesConfigurator.java

@@ -0,0 +1,93 @@
+package io.jenkins.plugins.casc.core;
+
+import edu.umd.cs.findbugs.annotations.CheckForNull;
+import edu.umd.cs.findbugs.annotations.NonNull;
+//import hudson.EnvVars;
+import hudson.EnvVars;
+import hudson.Extension;
+import hudson.slaves.EnvironmentVariablesNodeProperty;
+import hudson.slaves.EnvironmentVariablesNodeProperty.DescriptorImpl;
+import hudson.slaves.EnvironmentVariablesNodeProperty.Entry;
+import hudson.util.DescribableList;
+import hudson.util.PersistedList;
+import io.jenkins.plugins.casc.Attribute;
+import io.jenkins.plugins.casc.BaseConfigurator;
+import io.jenkins.plugins.casc.ConfigurationContext;
+import io.jenkins.plugins.casc.ConfiguratorException;
+import io.jenkins.plugins.casc.impl.attributes.MultivaluedAttribute;
+import io.jenkins.plugins.casc.model.CNode;
+import io.jenkins.plugins.casc.model.Mapping;
+import io.jenkins.plugins.casc.model.Sequence;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.stream.Collectors;
+import org.apache.commons.lang.StringUtils;
+
+@Extension
+public class GlobalNodePropertiesConfigurator extends BaseConfigurator<EnvironmentVariablesNodeProperty> {
+
+    @NonNull
+    @Override
+    public String getName() {
+        return "globalNodeProperties";
+    }
+
+    @Override
+    protected EnvironmentVariablesNodeProperty instance(Mapping mapping,
+        ConfigurationContext context) throws ConfiguratorException {
+        List<Entry> vars = getVarsAsList(mapping);
+        return new EnvironmentVariablesNodeProperty(vars);
+    }
+
+    @Override
+    public Class<EnvironmentVariablesNodeProperty> getTarget() {
+        return EnvironmentVariablesNodeProperty.class;
+    }
+
+    @NonNull
+    @Override
+    public Set<Attribute<EnvironmentVariablesNodeProperty, ?>> describe() {
+        Set<Attribute<EnvironmentVariablesNodeProperty, ?>> attrs = super.describe();
+        attrs.add(new MultivaluedAttribute<EnvironmentVariablesNodeProperty, EnvironmentVariablesNodeProperty.Entry>("env", Entry.class));
+        return attrs;
+    }
+
+    @NonNull
+    @Override
+    public EnvironmentVariablesNodeProperty configure(CNode c, ConfigurationContext context) throws ConfiguratorException {
+        Mapping mapping = c.asMapping();
+        List<Entry> variables = getVarsAsList(mapping);
+        return new EnvironmentVariablesNodeProperty(variables);
+    }
+
+    @CheckForNull
+    public CNode describe(EnvironmentVariablesNodeProperty instance, ConfigurationContext context) throws Exception {
+        Mapping mapping = new Mapping();
+        for (Attribute attribute : getAttributes()) {
+            CNode value = attribute.describe(instance, context);
+            // Clean empty vars
+            Sequence values = new Sequence();
+            value.asSequence().stream().filter(entry -> StringUtils.isNotBlank(entry.asMapping().get("value").toString()))
+                .forEach(values::add);
+            if (value != null) {
+                mapping.put(attribute.getName(), values);
+            }
+        }
+        return mapping;
+    }
+
+
+    private List<Entry> getVarsAsList(Mapping m) {
+        List<Entry> result = new ArrayList<>();
+        if (m.get("env") != null){
+            result = m.get("env").asSequence().stream()
+                .map(pair -> new Entry(pair.asMapping().get("key").asScalar().getValue(),
+                                              pair.asMapping().get("value").asScalar().getValue()))
+                .toList();
+        }
+        return result;
+    }
+}