diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/properties/builders/MultiValuePropertyBuilder.java b/pmd-core/src/main/java/net/sourceforge/pmd/properties/builders/MultiValuePropertyBuilder.java
index e3be94eac2..6405dd5770 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/properties/builders/MultiValuePropertyBuilder.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/properties/builders/MultiValuePropertyBuilder.java
@@ -4,7 +4,9 @@
 
 package net.sourceforge.pmd.properties.builders;
 
+import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collection;
 import java.util.List;
 
 import net.sourceforge.pmd.properties.MultiValuePropertyDescriptor;
@@ -36,8 +38,8 @@ public abstract class MultiValuePropertyBuilder<V, T extends MultiValuePropertyB
      * @return The same builder
      */
     @SuppressWarnings("unchecked")
-    public T defaultValues(List<V> val) {
-        this.defaultValues = val;
+    public T defaultValues(Collection<? extends V> val) {
+        this.defaultValues = new ArrayList<>(val);
         return (T) this;
     }
 
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/properties/builders/SinglePackagedPropertyBuilder.java b/pmd-core/src/main/java/net/sourceforge/pmd/properties/builders/SinglePackagedPropertyBuilder.java
index 3fb0b755bf..2f7219d14c 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/properties/builders/SinglePackagedPropertyBuilder.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/properties/builders/SinglePackagedPropertyBuilder.java
@@ -5,6 +5,7 @@
 package net.sourceforge.pmd.properties.builders;
 
 import java.util.Arrays;
+import java.util.Collection;
 
 
 /**
@@ -22,12 +23,35 @@ public abstract class SinglePackagedPropertyBuilder<V, T extends SinglePackagedP
     }
 
 
+    /**
+     * Specify the allowed package prefixes.
+     *
+     * @param packs The package prefixes
+     *
+     * @return The same builder
+     */
     @SuppressWarnings("unchecked")
-    public T legalPackageNames(String[] packs) {
+    public T legalPackageNames(String... packs) {
         if (packs != null) {
             this.legalPackageNames = Arrays.copyOf(packs, packs.length);
         }
         return (T) this;
     }
 
+
+    /**
+     * Specify the allowed package prefixes.
+     *
+     * @param packs The package prefixes
+     *
+     * @return The same builder
+     */
+    @SuppressWarnings("unchecked")
+    public T legalPackageNames(Collection<String> packs) {
+        if (packs != null) {
+            this.legalPackageNames = packs.toArray(new String[0]);
+        }
+        return (T) this;
+    }
+
 }