[JAVA][maven] .swagger-codegen-ignore wildcards are not honoured

Description

Maven plugin configuration:

<plugin>
  <groupId>io.swagger</groupId>
  <artifactId>swagger-codegen-maven-plugin</artifactId>
  <version>2.3.1</version>
    <executions>
      <execution>
        <id>generate-java-impl</id>
        <goals>
          <goal>generate</goal>
        </goals>
        <phase>generate-sources</phase>
        <configuration>
          <inputSpec>${project.basedir}/src/main/resources/core.yaml</inputSpec>
          <apiPackage>${project.groupId}.${project.artifactId}.swagger.api</apiPackage>
          <modelPackage>${project.groupId}.${project.artifactId}.swagger.model</modelPackage>
          <configOptions>
            <configPackage>${project.groupId}.${project.artifactId}.swagger.config</configPackage>
            <basePackage>${project.groupId}.${project.artifactId}.swagger</basePackage>
          </configOptions>
          <output>${project.basedir}</output>
          <language>spring</language>
          <generateSupportingFiles>true</generateSupportingFiles>
          <generateModelTests>false</generateModelTests>
          <generateApiTests>false</generateApiTests>
        </configuration>
      </execution>
    </executions>
</plugin>

Have created ${project.basedir}/.swagger-codegen-ignore file with contents

**/*
!src/**/*

And it wasn't honored during generation. Had overwritten my project files and got bunch of unneeded trash in root of my project.

Swagger-codegen version

Maven plugin version 2.3.1

Swagger declaration file content or url

irrelevant

Command line used for generation

mvn clean install

Steps to reproduce

All info above.

Related issues/PRs

None I know of.

Suggest a fix/enhancement

Make swagger-codegen-maven-plugin actually honour .swagger-codegen-ignore entries.

Currently have to manaully specify each trash file generated by plugin, which would not hold if it will be generating more of them in the future.

Reproduce the report using the Maven plugin configuration, .swagger-codegen-ignore containing / and !src/*/*, and mvn clean install. Start by tracing how the Maven plugin reads the ignore file during generation; done means wildcard entries are honored and unignored src files are generated without overwriting or creating the reported root-level files.