[MSHADE-452]Fix ServiceResourceTransformer not correct issue.

[hk-lrzy]

Background

We have java path as below

• org.apache.demo1
• org.apache.demo2

In maven-shade-plugin 3.2.1, we use relocation to process path and SPI Service file at the same time, and we will follow result.

<relocation>
    <pattern>org.apache.demo</pattern>
    <shadedPattern>shaded.org.apache.demo</shadedPattern>
</relocation> 

META-INF/services/shaded.org.apache.demo

But in maven-shaded-plugin 3.5.0, it can't work as before, alouthght it SPI file name alao could be changed, but the SPI file content will have no change.

I compared the differneces between the maven-shaded-plugin 3.5.0 and maven-shaded-plugin 3.2.1, finally find in maven-shaded-plugin 3.2.1, file content changed by follow code

public String applyToSourceContent( String sourceContent )
{
    if ( rawString )
    {
        return sourceContent;
    }
    else
    {
        return sourceContent.replaceAll( "\\b" + pattern, shadedPattern );
    }
}

but in maven-shaded-plugin 3.5.0, the code change to 

private String shadeSourceWithExcludes( String sourceContent, String patternFrom, String patternTo,
                                        Set<String> excludedPatterns )
{
    // Usually shading makes package names a bit longer, so make buffer 10% bigger than original source
    StringBuilder shadedSourceContent = new StringBuilder( sourceContent.length() * 11 / 10 );
    boolean isFirstSnippet = true;
    // Make sure that search pattern starts at word boundary and we look for literal ".", not regex jokers
    for ( String snippet : sourceContent.split( "\\b" + patternFrom.replace( ".", "[.]" + "\\b" ) ) )
    {
        boolean doExclude = false;
        for ( String excludedPattern : excludedPatterns )
        {
            if ( snippet.startsWith( excludedPattern ) )
            {
                doExclude = true;
                break;
            }
        }
        if ( isFirstSnippet )
        {
            shadedSourceContent.append( snippet );
            isFirstSnippet = false;
    }
        else
        {
            shadedSourceContent.append( doExclude ? patternFrom : patternTo ).append( snippet );
        }
    }
    return shadedSourceContent.toString();
} 

In my cases, source content is org.apache.demo1, pattern from is org.apache.demo, pattern to is shaded.org.apache.demo.

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[rmannibucau]

Hi @hk-lrzy , sorry for the delay (guess the PR popped during holidays). From my window this PR has the risk to revert some of the fixes done before. Long story short shade mixing the same API (relocation) for sources (variables, classes, packages), paths and other things, there is always a such a risk so ultimately I think a safer fix would make the relocated file more contextual (if (filePath ~ META-INF/services/xxxxxx then use relocateSPIFile()` to share the idea).

Hope it makes sense.