Add clarity in docs for using exportPathMap with getStaticPaths (#…

…39813)

This PR adds a warning note for using the exportPathMap function with getStaticPaths. Any routes defined with EPM will get overridden if that page uses GSP.
Bug

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 Integration tests added
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Feature

 Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
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Documentation / Examples

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 The examples guidelines are followed from our contributing doc

docs/advanced-features/static-html-export.md

@@ -31,6 +31,8 @@ Running `npm run build` will generate an `out` directory.
 
 For more advanced scenarios, you can define a parameter called [`exportPathMap`](/docs/api-reference/next.config.js/exportPathMap.md) in your [`next.config.js`](/docs/api-reference/next.config.js/introduction.md) file to configure exactly which pages will be generated.
 
+> **Warning**: Using `exportPathMap` for defining routes with any `getStaticPaths` powered page is now ignored and gets overridden. We recommend not to use them together.
+
 ## Supported Features
 
 The majority of core Next.js features needed to build a static site are supported, including:

docs/api-reference/next.config.js/exportPathMap.md

@@ -40,7 +40,7 @@ module.exports = {
 }
 ```
 
-Note: the `query` field in `exportPathMap` cannot be used with [automatically statically optimized pages](/docs/advanced-features/automatic-static-optimization) or [`getStaticProps` pages](/docs/basic-features/data-fetching/get-static-props.md) as they are rendered to HTML files at build-time and additional query information cannot be provided during `next export`.
+> Note: the `query` field in `exportPathMap` cannot be used with [automatically statically optimized pages](/docs/advanced-features/automatic-static-optimization) or [`getStaticProps` pages](/docs/basic-features/data-fetching/get-static-props.md) as they are rendered to HTML files at build-time and additional query information cannot be provided during `next export`.
 
 The pages will then be exported as HTML files, for example, `/about` will become `/about.html`.
 
@@ -79,6 +79,8 @@ module.exports = {
 next export -o outdir
 ```
 
+> **Warning**: Using `exportPathMap` for defining routes with any `getStaticPaths` powered page is now ignored and gets overridden. We recommend not to use them together.
+
 ## Related
 
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