schemagen tool generates schema with standard file names schema1.xsd schema2.xsd etc.

How to generate Aircraft.xsd and BaseEntity.xsd for the following source,

/* core.BaseEntity.java */
package core;

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlType;

@XmlAccessorType(XmlAccessType.PROPERTY)

@XmlType(namespace="sampleApp", name = "BaseEntityType", propOrder = {
"id"
})


public class BaseEntity {

private String _id;

public String getId () {
return this._id;
}

public void setId (String id) {
this._id = id;
}
}

and

/* gen.Aircraft.java */

package gen;

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlType;

import core.BaseEntity;

@XmlAccessorType(XmlAccessType.PROPERTY)

@XmlType(namespace="sampleApp", name = "AirCraftType", propOrder = {
"aircraftName",
"capacity"
})


public class AirCraft extends BaseEntity {

private String _aircraftName;
private int _capacity;

public String getAircraftName () {
return this._aircraftName;
}

public void setAircraftName (String aircraftName) {
this._aircraftName = aircraftName;
}

public int getCapacity () {
return this._capacity;
}

public void setCapacity (int capacity) {
this._capacity = capacity;
}
}