Fix initialisation bug

pmd-core/src/main/java/net/sourceforge/pmd/AbstractPropertyDescriptorFactory.java

@@ -4,7 +4,7 @@
 
 package net.sourceforge.pmd;
 
-import static net.sourceforge.pmd.PropertyDescriptor.CORE_FIELD_TYPES_BY_KEY;
+import static net.sourceforge.pmd.PropertyDescriptor.CORE_EXPECTED_FIELDS;
 import static net.sourceforge.pmd.PropertyDescriptorField.DEFAULT_VALUE;
 import static net.sourceforge.pmd.PropertyDescriptorField.DELIMITER;
 import static net.sourceforge.pmd.PropertyDescriptorField.DESCRIPTION;
@@ -19,6 +19,8 @@ import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
 
+import org.apache.commons.lang3.StringUtils;
+
 import net.sourceforge.pmd.util.StringUtil;
 
 /**
@@ -30,26 +32,18 @@ import net.sourceforge.pmd.util.StringUtil;
  */
 public abstract class AbstractPropertyDescriptorFactory<T> implements PropertyDescriptorFactory<T> {
 
-
-
-
-    static {
-        System.err.println(CORE_FIELD_TYPES_BY_KEY);
-    }
-
-
     private final Class<?> valueType;
 
     /**
      * Denote the identifiers of the expected fields paired with booleans
-     * denoting whether they are required (non-null) or not.
+     * denoting whether they are required or not.
      */
     private final Map<PropertyDescriptorField, Boolean> expectedFields;
 
 
     public AbstractPropertyDescriptorFactory(Class<?> theValueType) {
         valueType = theValueType;
-        expectedFields = CORE_FIELD_TYPES_BY_KEY;
+        expectedFields = CORE_EXPECTED_FIELDS;
     }
 
 
@@ -57,12 +51,12 @@ public abstract class AbstractPropertyDescriptorFactory<T> implements PropertyDe
 
         valueType = theValueType;
         if (additionalFieldTypesByKey == null) {
-            expectedFields = CORE_FIELD_TYPES_BY_KEY;
+            expectedFields = CORE_EXPECTED_FIELDS;
             return;
         }
         Map<PropertyDescriptorField, Boolean> temp
-            = new HashMap<>(CORE_FIELD_TYPES_BY_KEY.size() + additionalFieldTypesByKey.size());
+            = new HashMap<>(CORE_EXPECTED_FIELDS.size() + additionalFieldTypesByKey.size());
-        temp.putAll(CORE_FIELD_TYPES_BY_KEY);
+        temp.putAll(CORE_EXPECTED_FIELDS);
         temp.putAll(additionalFieldTypesByKey);
 
         expectedFields = Collections.unmodifiableMap(temp);
@@ -116,7 +110,7 @@ public abstract class AbstractPropertyDescriptorFactory<T> implements PropertyDe
      */
     protected String defaultValueIn(Map<PropertyDescriptorField, String> valuesById) {
         String deft = valuesById.get(DEFAULT_VALUE);
-        if (StringUtil.isEmpty(deft)) {
+        if (isValueMissing(deft)) {
             throw new RuntimeException("Default value was null, empty, or missing");
         }
         return deft;
@@ -125,7 +119,7 @@ public abstract class AbstractPropertyDescriptorFactory<T> implements PropertyDe
 
     @Override
     public final PropertyDescriptor<T> createWith(Map<PropertyDescriptorField, String> valuesById) {
-      //  checkRequiredFields(valuesById);
+        checkRequiredFields(valuesById);
         return createWith(valuesById, false);
     }
 
@@ -133,7 +127,7 @@ public abstract class AbstractPropertyDescriptorFactory<T> implements PropertyDe
     /** Checks whether all required fields are present in the map. */
     private void checkRequiredFields(Map<PropertyDescriptorField, String> valuesById) {
         for (Entry<PropertyDescriptorField, Boolean> entry : expectedFields.entrySet()) {
-            if (entry.getValue() && StringUtil.isEmpty(valuesById.get(entry.getKey()))) {
+            if (entry.getValue() && isValueMissing(valuesById.get(entry.getKey()))) {
                 throw new RuntimeException("Missing required value for key: " + entry.getKey());
             }
         }
@@ -249,7 +243,7 @@ public abstract class AbstractPropertyDescriptorFactory<T> implements PropertyDe
             characterStr = valuesById.get(DELIMITER).trim();
         }
 
-        if (StringUtil.isEmpty(characterStr)) {
+        if (StringUtils.isBlank(characterStr)) {
             return defaultDelimiter;
         }
 
@@ -272,7 +266,7 @@ public abstract class AbstractPropertyDescriptorFactory<T> implements PropertyDe
     protected static String[] minMaxFrom(Map<PropertyDescriptorField, String> valuesById) {
         String min = minValueIn(valuesById);
         String max = maxValueIn(valuesById);
-        if (StringUtil.isEmpty(min) || StringUtil.isEmpty(max)) {
+        if (StringUtils.isBlank(min) || StringUtils.isBlank(max)) {
             throw new RuntimeException("min and max values must be specified");
         }
         return new String[] {min, max};
@@ -291,7 +285,7 @@ public abstract class AbstractPropertyDescriptorFactory<T> implements PropertyDe
 
     protected static String[] legalPackageNamesIn(Map<PropertyDescriptorField, String> valuesById, char delimiter) {
         String names = valuesById.get(LEGAL_PACKAGES);
-        if (StringUtil.isEmpty(names)) {
+        if (StringUtils.isBlank(names)) {
             return null;
         }
         return StringUtil.substringsOf(names, delimiter);
@@ -299,18 +293,19 @@ public abstract class AbstractPropertyDescriptorFactory<T> implements PropertyDe
 
 
     /**
-     * Returns a map describing which fields are required to build an
+     * Returns a map describing which fields are required to build a property using this factory. The parameters are
+     * added to the {@link PropertyDescriptor#CORE_EXPECTED_FIELDS}, which are required for all descriptors.
      *
-     * @param otherKeys
+     * @param otherKeys Additional keys
-     * @param otherValues
+     * @param otherValues Whether the corresponding keys are required or not
      *
-     * @return
+     * @return The complete map of expected fields.
      */
-    public static Map<PropertyDescriptorField, Boolean> expectedFieldTypesWith(PropertyDescriptorField[] otherKeys,
+    static Map<PropertyDescriptorField, Boolean> expectedFieldTypesWith(PropertyDescriptorField[] otherKeys,
                                                                                Boolean[] otherValues) {
         Map<PropertyDescriptorField, Boolean> largerMap = new HashMap<>(
-            otherKeys.length + CORE_FIELD_TYPES_BY_KEY.size());
+            otherKeys.length + CORE_EXPECTED_FIELDS.size());
-        largerMap.putAll(CORE_FIELD_TYPES_BY_KEY);
+        largerMap.putAll(CORE_EXPECTED_FIELDS);
         for (int i = 0; i < otherKeys.length; i++) {
             largerMap.put(otherKeys[i], otherValues[i]);
         }

pmd-core/src/main/java/net/sourceforge/pmd/MultiValuePropertyDescriptor.java

@@ -7,8 +7,10 @@ package net.sourceforge.pmd;
 import java.util.List;
 
 /**
- * Specializes property descriptors for single valued descriptors. For this type of property, the return value of the
+ * Specializes property descriptors for multi valued descriptors. For this type of property, the return value of the
- * {@link #type()} method must be the class literal of the type parameter of the interface {@link PropertyDescriptor}.
+ * {@link #type()} method must be the class literal of the type parameter of this interface, which is the type of the
+ * components of the list (not the type of the list). Notice that for implementors, the type parameter of this interface
+ * is <i>not</i> the same as the type parameter of {@link PropertyDescriptor} they inherit!
  *
  * @param <V> The type of value this descriptor works with. This is the type of the list's component.
  *

pmd-core/src/main/java/net/sourceforge/pmd/NumericPropertyDescriptor.java

@@ -9,7 +9,7 @@ import static net.sourceforge.pmd.PropertyDescriptorField.MIN;
 
 import java.util.Map;
 
-import net.sourceforge.pmd.lang.rule.properties.PropertyDescriptorUtil;
+import net.sourceforge.pmd.lang.rule.properties.ExpectedFieldsBuilder;
 
 /**
  * Defines a descriptor type whose instance values are required to lie within
@@ -22,7 +22,7 @@ import net.sourceforge.pmd.lang.rule.properties.PropertyDescriptorUtil;
 public interface NumericPropertyDescriptor<T> extends PropertyDescriptor<T> {
 
     Map<PropertyDescriptorField, Boolean> NUMBER_FIELD_TYPES_BY_KEY
-        = PropertyDescriptorUtil.expectedFields().put(MIN, true).put(MAX, true).get();
+        = ExpectedFieldsBuilder.instance().put(MIN, true).put(MAX, true).build();
 
 
     /**

pmd-core/src/main/java/net/sourceforge/pmd/PropertyDescriptor.java

@@ -11,7 +11,7 @@ import static net.sourceforge.pmd.PropertyDescriptorField.NAME;
 
 import java.util.Map;
 
-import net.sourceforge.pmd.lang.rule.properties.PropertyDescriptorUtil.ExpectedFieldsBuilder;
+import net.sourceforge.pmd.lang.rule.properties.ExpectedFieldsBuilder;
 
 /**
  * Property value descriptor that defines the use & requirements for setting
@@ -35,13 +35,13 @@ import net.sourceforge.pmd.lang.rule.properties.PropertyDescriptorUtil.ExpectedF
 public interface PropertyDescriptor<T> extends Comparable<PropertyDescriptor<?>> {
 
     /** Default expected fields. Unmodifiable. */
-    Map<PropertyDescriptorField, Boolean> CORE_FIELD_TYPES_BY_KEY
+    Map<PropertyDescriptorField, Boolean> CORE_EXPECTED_FIELDS
-        = (new ExpectedFieldsBuilder())
+        = ExpectedFieldsBuilder.instance()
         .put(NAME, true)
         .put(DESCRIPTION, true)
         .put(DEFAULT_VALUE, true)
         .put(DELIMITER, false)
-        .get();
+        .build();
 
 
     /**

pmd-core/src/main/java/net/sourceforge/pmd/RuleSet.java

@@ -16,6 +16,8 @@ import java.util.Objects;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
+import org.apache.commons.lang3.StringUtils;
+
 import net.sourceforge.pmd.benchmark.Benchmark;
 import net.sourceforge.pmd.benchmark.Benchmarker;
 import net.sourceforge.pmd.cache.ChecksumAware;
@@ -179,7 +181,7 @@ public class RuleSet implements ChecksumAware {
          * @return The same builder, for a fluid programming interface
          */
         public RuleSetBuilder addRuleByReference(final String ruleSetFileName, final Rule rule) {
-            if (StringUtil.isEmpty(ruleSetFileName)) {
+            if (StringUtils.isBlank(ruleSetFileName)) {
                 throw new RuntimeException(
                         "Adding a rule by reference is not allowed with an empty rule set file name.");
             }
@@ -246,7 +248,7 @@ public class RuleSet implements ChecksumAware {
          */
         public RuleSetBuilder addRuleSetByReference(final RuleSet ruleSet, final boolean allRules,
                 final String... excludes) {
-            if (StringUtil.isEmpty(ruleSet.getFileName())) {
+            if (StringUtils.isBlank(ruleSet.getFileName())) {
                 throw new RuntimeException(
                         "Adding a rule by reference is not allowed with an empty rule set file name.");
             }

pmd-core/src/main/java/net/sourceforge/pmd/RuleSetFactory.java

@@ -4,6 +4,8 @@
 
 package net.sourceforge.pmd;
 
+import static net.sourceforge.pmd.PropertyDescriptorField.DEFAULT_VALUE;
+
 import java.io.IOException;
 import java.io.InputStream;
 import java.util.ArrayList;
@@ -23,6 +25,7 @@ import javax.xml.parsers.DocumentBuilder;
 import javax.xml.parsers.DocumentBuilderFactory;
 import javax.xml.parsers.ParserConfigurationException;
 
+import org.apache.commons.lang3.StringUtils;
 import org.w3c.dom.Document;
 import org.w3c.dom.Element;
 import org.w3c.dom.Node;
@@ -414,7 +417,7 @@ public class RuleSetFactory {
         String ref = ruleElement.getAttribute("ref");
         if (ref.endsWith("xml")) {
             parseRuleSetReferenceNode(ruleSetReferenceId, ruleSetBuilder, ruleElement, ref);
-        } else if (StringUtil.isEmpty(ref)) {
+        } else if (StringUtils.isBlank(ref)) {
             parseSingleRuleNode(ruleSetReferenceId, ruleSetBuilder, ruleNode);
         } else {
             parseRuleReferenceNode(ruleSetReferenceId, ruleSetBuilder, ruleNode, ref, withDeprecatedRuleReferences);
@@ -812,13 +815,13 @@ public class RuleSetFactory {
 
         Element propertyElement = (Element) propertyNode;
         String typeId = propertyElement.getAttribute(PropertyDescriptorField.TYPE.attributeName());
-        String strValue = propertyElement.getAttribute(PropertyDescriptorField.DEFAULT_VALUE.attributeName());
+        String strValue = propertyElement.getAttribute(DEFAULT_VALUE.attributeName());
-        if (StringUtil.isEmpty(strValue)) {
+        if (StringUtils.isBlank(strValue)) {
             strValue = valueFrom(propertyElement);
         }
 
         // Setting of existing property, or defining a new property?
-        if (StringUtil.isEmpty(typeId)) {
+        if (StringUtils.isBlank(typeId)) {
             String name = propertyElement.getAttribute(PropertyDescriptorField.NAME.attributeName());
 
             PropertyDescriptor<?> propertyDescriptor = rule.getPropertyDescriptor(name);
@@ -842,9 +845,19 @@ public class RuleSetFactory {
         // populate a map of values for an individual descriptor
         for (PropertyDescriptorField field : valueKeys) {
             String valueStr = propertyElement.getAttribute(field.attributeName());
+            if (valueStr != null)
             values.put(field, valueStr);
         }
 
+        if (StringUtils.isBlank(values.get(DEFAULT_VALUE))) {
+            NodeList children = propertyElement.getElementsByTagName(DEFAULT_VALUE.attributeName());
+            if (children.getLength() == 1) {
+                values.put(DEFAULT_VALUE, children.item(0).getTextContent());
+            } else {
+                throw new RuntimeException("No value defined!");
+            }
+        }
+
         // casting is not pretty but prevents the interface from having this method
         PropertyDescriptor<?> desc = ((AbstractPropertyDescriptorFactory) pdFactory).createExternalWith(values);
 

pmd-core/src/main/java/net/sourceforge/pmd/RuleSetReferenceId.java

@@ -408,7 +408,7 @@ public class RuleSetReferenceId {
      */
     public InputStream getInputStream(ClassLoader classLoader) throws RuleSetNotFoundException {
         if (externalRuleSetReferenceId == null) {
-            InputStream in = StringUtil.isEmpty(ruleSetFileName) ? null
+            InputStream in = StringUtils.isBlank(ruleSetFileName) ? null
                     : ResourceLoader.loadResourceAsStream(ruleSetFileName, classLoader);
             if (in == null) {
                 throw new RuleSetNotFoundException("Can't find resource '" + ruleSetFileName + "' for rule '" + ruleName

pmd-core/src/main/java/net/sourceforge/pmd/lang/rule/properties/CharacterMultiProperty.java

@@ -9,6 +9,8 @@ import java.util.Arrays;
 import java.util.List;
 import java.util.Map;
 
+import org.apache.commons.lang3.StringUtils;
+
 import net.sourceforge.pmd.PropertyDescriptorFactory;
 import net.sourceforge.pmd.PropertyDescriptorField;
 import net.sourceforge.pmd.lang.rule.properties.ValueParser.Companion;
@@ -28,7 +30,7 @@ public final class CharacterMultiProperty extends AbstractMultiValueProperty<Cha
 
             @Override
             protected boolean isValueMissing(String value) {
-                return StringUtil.isMissing(value);
+                return StringUtils.isEmpty(value);
             }
 
             @Override

pmd-core/src/main/java/net/sourceforge/pmd/lang/rule/properties/CharacterProperty.java

@@ -8,6 +8,8 @@ import static net.sourceforge.pmd.lang.rule.properties.ValueParser.CHARACTER_PAR
 
 import java.util.Map;
 
+import org.apache.commons.lang3.StringUtils;
+
 import net.sourceforge.pmd.PropertyDescriptorFactory;
 import net.sourceforge.pmd.PropertyDescriptorField;
 import net.sourceforge.pmd.util.StringUtil;
@@ -25,7 +27,7 @@ public final class CharacterProperty extends AbstractSingleValueProperty<Charact
 
             @Override
             protected boolean isValueMissing(String value) {
-                return StringUtil.isMissing(value);
+                return StringUtils.isEmpty(value);
             }
 
             @Override

pmd-core/src/main/java/net/sourceforge/pmd/lang/rule/properties/DoubleProperty.java

@@ -21,18 +21,18 @@ import net.sourceforge.pmd.PropertyDescriptorField;
  */
 public final class DoubleProperty extends AbstractNumericProperty<Double> {
 
+    /** Factory. */
     public static final PropertyDescriptorFactory<Double> FACTORY // @formatter:off
             = new SingleValuePropertyDescriptorFactory<Double>(Double.class, NUMBER_FIELD_TYPES_BY_KEY) {
                 @Override
                 public DoubleProperty createWith(Map<PropertyDescriptorField, String> valuesById,
                                                  boolean isDefinedExternally) {
                     final String[] minMax = minMaxFrom(valuesById);
-                    System.out.println(Arrays.asList(minMax));
                     return new DoubleProperty(nameIn(valuesById),
                                               descriptionIn(valuesById),
-                                              DOUBLE_PARSER.valueOf(minMax[0]),
+                                              doubleFrom(minMax[0]),
-                                              DOUBLE_PARSER.valueOf(minMax[1]),
+                                              doubleFrom(minMax[1]),
-                                              DOUBLE_PARSER.valueOf(defaultValueIn(valuesById)),
+                                              doubleFrom(defaultValueIn(valuesById)),
                                               0f,
                                               isDefinedExternally);
                 }
@@ -73,8 +73,8 @@ public final class DoubleProperty extends AbstractNumericProperty<Double> {
      *
      * @return Parsed Double
      */
-    public static Double doubleFrom(String numberString) {
+    private static Double doubleFrom(String numberString) {
-        return Double.valueOf(numberString);
+        return DOUBLE_PARSER.valueOf(numberString);
     }
 
 

pmd-core/src/main/java/net/sourceforge/pmd/lang/rule/properties/ExpectedFieldsBuilder.java

@@ -0,0 +1,59 @@
+/**
+ * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
+ */
+
+package net.sourceforge.pmd.lang.rule.properties;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+
+import net.sourceforge.pmd.PropertyDescriptorField;
+
+/** Builder for an expected fields map. */
+public final class ExpectedFieldsBuilder {
+
+    private final Map<PropertyDescriptorField, Boolean> requiredFields = new HashMap<>();
+
+
+    private ExpectedFieldsBuilder() {
+
+    }
+
+
+    /**
+     * Adds a mapping of field/ required to the map.
+     *
+     * @param field      The field to expect
+     * @param isRequired Whether it's required or not
+     *
+     * @return This instance, so that we have a fluent interface
+     */
+    public ExpectedFieldsBuilder put(PropertyDescriptorField field, boolean isRequired) {
+        requiredFields.put(field, isRequired);
+        return this;
+    }
+
+
+    /**
+     * Gets an immutable map containing the fields we've put here.
+     *
+     * @return The map of field/ isRequired mappings
+     */
+    public Map<PropertyDescriptorField, Boolean> build() {
+        return Collections.unmodifiableMap(requiredFields);
+    }
+
+
+    /**
+     * Gets a builder for a required fields map.
+     *
+     * @return A builder
+     *
+     * @see ExpectedFieldsBuilder
+     */
+    public static ExpectedFieldsBuilder instance() {
+        return new ExpectedFieldsBuilder();
+    }
+
+}

pmd-core/src/main/java/net/sourceforge/pmd/lang/rule/properties/FloatProperty.java

@@ -92,4 +92,6 @@ public final class FloatProperty extends AbstractNumericProperty<Float> {
     protected Float createFrom(String value) {
         return FLOAT_PARSER.valueOf(value);
     }
+
+
 }

pmd-core/src/main/java/net/sourceforge/pmd/lang/rule/properties/IntegerProperty.java

@@ -19,6 +19,7 @@ import net.sourceforge.pmd.PropertyDescriptorField;
  */
 public final class IntegerProperty extends AbstractNumericProperty<Integer> {
 
+    /** Factory. */
     public static final PropertyDescriptorFactory<Integer> FACTORY // @formatter:off
         = new SingleValuePropertyDescriptorFactory<Integer>(Integer.class, NUMBER_FIELD_TYPES_BY_KEY) {
 
@@ -36,11 +37,6 @@ public final class IntegerProperty extends AbstractNumericProperty<Integer> {
         }; // @formatter:on
 
 
-    static {
-        System.err.println(FACTORY);
-    }
-
-
     /**
      * Constructor that limits itself to a single value within the specified limits.
      *

pmd-core/src/main/java/net/sourceforge/pmd/lang/rule/properties/PropertyDescriptorUtil.java

@@ -9,7 +9,6 @@ import java.util.HashMap;
 import java.util.Map;
 
 import net.sourceforge.pmd.PropertyDescriptorFactory;
-import net.sourceforge.pmd.PropertyDescriptorField;
 
 /**
  * Utility class allowing to find the factory of a specific type of descriptor. That's used to define descriptors in
@@ -24,7 +23,6 @@ public final class PropertyDescriptorUtil {
 
     static {
         Map<String, PropertyDescriptorFactory<?>> temp = new HashMap<>(18);
-
         temp.put("Boolean", BooleanProperty.FACTORY);
         temp.put("List<Boolean>", BooleanMultiProperty.FACTORY);
 
@@ -33,6 +31,7 @@ public final class PropertyDescriptorUtil {
         temp.put("Character", CharacterProperty.FACTORY);
         temp.put("List<Character>", CharacterMultiProperty.FACTORY);
 
+
         temp.put("Integer", IntegerProperty.FACTORY);
         temp.put("List<Integer>", IntegerMultiProperty.FACTORY);
         temp.put("Long", LongProperty.FACTORY);
@@ -41,7 +40,6 @@ public final class PropertyDescriptorUtil {
         temp.put("List<Float>", FloatMultiProperty.FACTORY);
         temp.put("Double", DoubleProperty.FACTORY);
         temp.put("List<Double>", DoubleMultiProperty.FACTORY);
-
         //    temp.put("Enum", EnumeratedProperty.FACTORY); // TODO:cf implement that
         //    temp.put("List<Enum>", EnumeratedMultiProperty.FACTORY);
 
@@ -90,52 +88,4 @@ public final class PropertyDescriptorUtil {
     }
 
 
-    /**
-     * Gets a builder for a required fields map.
-     *
-     * @return A builder
-     *
-     * @see ExpectedFieldsBuilder
-     */
-    public static ExpectedFieldsBuilder expectedFields() {
-        return new ExpectedFieldsBuilder();
-    }
-
-
-    /** Builder for an expected fields map. */
-    public static final class ExpectedFieldsBuilder {
-
-        Map<PropertyDescriptorField, Boolean> requiredFields = new HashMap<>();
-
-
-        public ExpectedFieldsBuilder() {
-
-        }
-
-
-        /**
-         * Adds a mapping of field/ required to the map.
-         *
-         * @param field      The field to expect
-         * @param isRequired Whether it's required or not
-         *
-         * @return This instance, so that we have a fluent interface
-         */
-        public ExpectedFieldsBuilder put(PropertyDescriptorField field, boolean isRequired) {
-            requiredFields.put(field, isRequired);
-            return this;
-        }
-
-
-        /**
-         * Gets an immutable map containing the fields we've put here.
-         *
-         * @return The map of field/ isRequired mappings
-         */
-        public Map<PropertyDescriptorField, Boolean> get() {
-            return Collections.unmodifiableMap(requiredFields);
-        }
-
-    }
-
 }

pmd-core/src/main/java/net/sourceforge/pmd/lang/rule/properties/StringMultiProperty.java

@@ -10,6 +10,8 @@ import java.util.Arrays;
 import java.util.List;
 import java.util.Map;
 
+import org.apache.commons.lang3.StringUtils;
+
 import net.sourceforge.pmd.PropertyDescriptorFactory;
 import net.sourceforge.pmd.PropertyDescriptorField;
 import net.sourceforge.pmd.lang.rule.properties.ValueParser.Companion;
@@ -30,7 +32,7 @@ public final class StringMultiProperty extends AbstractMultiValueProperty<String
 
             @Override
             protected boolean isValueMissing(String value) {
-                return StringUtil.isMissing(value);
+                return StringUtils.isEmpty(value);
             }
 
             @Override

pmd-core/src/main/java/net/sourceforge/pmd/lang/rule/properties/StringProperty.java

@@ -6,6 +6,8 @@ package net.sourceforge.pmd.lang.rule.properties;
 
 import java.util.Map;
 
+import org.apache.commons.lang3.StringUtils;
+
 import net.sourceforge.pmd.PropertyDescriptorFactory;
 import net.sourceforge.pmd.PropertyDescriptorField;
 import net.sourceforge.pmd.util.StringUtil;
@@ -24,7 +26,7 @@ public final class StringProperty extends AbstractSingleValueProperty<String> {
 
             @Override
             protected boolean isValueMissing(String value) {
-                return StringUtil.isMissing(value);
+                return StringUtils.isEmpty(value);
             }
 
             @Override

pmd-core/src/main/java/net/sourceforge/pmd/util/StringUtil.java

@@ -8,6 +8,8 @@ import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
 
+import org.apache.commons.lang3.StringUtils;
+
 /**
  * A number of String-specific utility methods for use by PMD or its IDE
  * plugins.
@@ -100,14 +102,14 @@ public final class StringUtil {
     /**
      * Returns true if the value arg is either null, empty, or full of
      * whitespace characters. More efficient that calling
-     * (string).trim().length() == 0
+     * (string).trim().length() == 0.
      *
-     * @param value
+     * @param value String to test
      *
      * @return <code>true</code> if the value is empty, <code>false</code> otherwise.
      */
     public static boolean isEmpty(String value) {
-        return isMissing(value) || nullSafeIsBlank(value);
+        return StringUtils.isBlank(value);
     }
 
 
@@ -119,41 +121,7 @@ public final class StringUtil {
      * @return True if the argument is null or the empty string
      */
     public static boolean isMissing(String value) {
-
+        return StringUtils.isEmpty(value);
-        if (value == null || "".equals(value)) {
-            return true;
-        }
-
-        return false;
-    }
-
-
-    /** Argument must not be null. */
-    private static boolean nullSafeIsBlank(String value) {
-        for (int i = 0; i < value.length(); i++) {
-            if (!Character.isWhitespace(value.charAt(i))) {
-                return false;
-            }
-        }
-
-        return true;
-    }
-
-
-    /**
-     * Returns true if the argument is null or entirely composed of whitespace characters.
-     *
-     * @param value String to test
-     *
-     * @return True if the argument is null or entirely composed of whitespace characters.
-     */
-    public static boolean isBlank(String value) {
-
-        if (value == null) {
-            return true;
-        }
-
-        return nullSafeIsBlank(value);
     }