AXIS2-6074 Return null for empty enum values instead of throwing

When an empty XML element is sent for an enum field (e.g., <eventType/>),
the generated fromValue() method looked up the empty string in the enum
table, got null, and threw IllegalArgumentException. This caused a
cryptic SOAP fault ("unknown") with null HTTP status.

Fix: in both bean and helpermode templates, allow null/empty values to
return null from fromValue() instead of throwing. The bean template
previously had this guard only for string property types — now it
applies to all types. The helpermode template had no guard at all.

This restores the Axis2 1.6 behavior where empty enum elements were
handled gracefully.

Author: robertlazarski

modules/adb-codegen/src/org/apache/axis2/schema/template/ADBBeanTemplate-bean.xsl

@@ -1811,7 +1811,8 @@
                        </xsl:choose>
 
                     // handle unexpected enumeration values properly
-                    if (enumeration == null  <xsl:if test="$propertyType='string'">&amp;&amp; !((value == null) || (value.equals("")))</xsl:if>) {
+                    // AXIS2-6074: allow null/empty values for all types, not just string
+                    if (enumeration == null &amp;&amp; value != null &amp;&amp; !value.toString().trim().isEmpty()) {
                         <xsl:choose>
                             <xsl:when test="$ignoreunexpected">
                                 log.warn("Unexpected value " + value + " for enumeration <xsl:value-of select="$name"/>");

modules/adb-codegen/src/org/apache/axis2/schema/template/ADBBeanTemplate-helpermode.xsl

@@ -253,7 +253,8 @@
                                        </xsl:otherwise>
                                    </xsl:choose>
 
-                                if (enumeration==null) throw new java.lang.IllegalArgumentException();
+                                // AXIS2-6074: return null for empty/null values instead of throwing
+                                if (enumeration==null &amp;&amp; value != null &amp;&amp; !value.toString().trim().isEmpty()) throw new java.lang.IllegalArgumentException();
                                 return enumeration;
                             }
                             public static <xsl:value-of select="$name"/> fromString(java.lang.String value)