Recently I have stumbled upon an error when trying to generate JAXB annotated classes using Jaxb2 Maven plugin and XJC goal:
Failed to read schema document 'xjc.xsd', because 'file' access is not allowed due to restriction set by the accessExternalSchema property.
This is a permissions problem which can be fixed by a simple VM argument.
I have found that best solution when using IntelliJ Idea is to setup Maven VM arguments (Settings >> Maven >> Runner - VM Arguments). Another solution when using command line is to set MAVEN_OPTS environment variable with the mentioned VM argument: