Finally I figured out that was wrong regarding this issue was the place where I placed the CACHED_HTTP_CLIENT parameter:
Incorrect code:
serviceClient.getOptions().setProperty(HTTPConstants.CACHED_HTTP_CLIENT, httpClient);
Correct code:
ConfigurationContext axisContext;
try {
axisContext = ConfigurationContextFactory.createDefaultConfigurationContext();
} catch (Exception e) {
throw new AxisFault(e.getMessage());
}
axisContext.setProperty(HTTPConstants.CACHED_HTTP_CLIENT, httpClient);
stub = new MyStub(axisContext, url);