JAXB, xsd to java,

common.xsd

<?xml version="1.0" encoding="UTF-8"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"  
	targetNamespace="urn:com:sample:common" 
	xmlns="urn:com:sample:common" 
	elementFormDefault="qualified" 
	attributeFormDefault="unqualified">
	<!-- here, declare namespace: targetNamespace and xmlns-->
	
	<xsd:simpleType name="CurrencyCodeEnum">
		<xsd:restriction base="xsd:string">
			<xsd:minLength value="3"/>
			<xsd:maxLength value="3"/>
			<xsd:pattern value=""/>
			<xsd:enumeration value="AED"/>
			<xsd:enumeration value="AFN"/>
			<xsd:enumeration value="ALL"/>
			<xsd:enumeration value="AMD"/>
		</xsd:restriction>
	</xsd:simpleType>
</xsd:schema>

help.sh

#!/bin/bash

output='gen'

rm -rf $output
mkdir $output

# generate java to "gen" folder
xjc -d $output Recipe.xsd

Recipe.xsd

<?xml version="1.0" encoding="UTF-8"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"
	xmlns="urn:com:sample:Finance" 
	targetNamespace="urn:com:sample:Finance" 
	xmlns:prefixName="urn:com:sample:common" 
	elementFormDefault="qualified" 
	attributeFormDefault="unqualified">
	<!-- here, see: 'xmlns:prefixName'  -->

	<xsd:import schemaLocation="common.xsd" namespace="urn:com:sample:common"/> <!-- add import here -->
	
	<xsd:complexType name="Amount">
		<xsd:sequence>
			
			<xsd:element name="Currency" 
				type="prefixName:CurrencyCodeEnum" /> <!-- imported type-->
		</xsd:sequence>
	</xsd:complexType>
</xsd:schema>