Document counterintuitive AddHostedService behavior

[MichaelDeutschCoding]

See dotnet/runtime#38751 for discussion about this issue.

Summary

Add documentation describing the behavior when multiple services (of the same class) are added when calling Microsoft.Extensions.DependencyInjection.IServiceCollection.AddHostedService<THostedService>.

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Issue Details

---

See dotnet/runtime#38751 for discussion about this issue.

Summary

Add documentation describing the behavior when multiple services (of the same class) are added when calling Microsoft.Extensions.DependencyInjection.IServiceCollection.AddHostedService<THostedService>.

Author:	MichaelDeutschCoding
Assignees:	-
Labels:	area-Extensions-DependencyInjection, community-contribution
Milestone:	-

[learn-build-service-prod]

Learn Build status updates of commit ecf55f2:

❌ Validation status: errors

Please follow instructions here which may help to resolve issue.

File	Status	Preview URL	Details
	❌Error		Details
xml/Microsoft.Extensions.DependencyInjection/ServiceCollectionHostedServiceExtensions.xml	❌Error		Details

• Line 0, Column 0: [Error: ECMA2Yaml_File_LoadFailed] Failed to load 1 files, aborting...

xml/Microsoft.Extensions.DependencyInjection/ServiceCollectionHostedServiceExtensions.xml

• Line 0, Column 0: [Error: ECMA2Yaml_InternalError]

Intenal Several Error: System.Xml.XmlException: The ',' character, hexadecimal value 0x2C, cannot be included in a name. Line 72, position 268.
   at System.Xml.XmlTextReaderImpl.Throw(Exception e)
   at System.Xml.XmlTextReaderImpl.Throw(String res, String[] args)
   at System.Xml.XmlTextReaderImpl.Throw(Int32 pos, String res, String[] args)
   at System.Xml.XmlTextReaderImpl.ParseElement()
   at System.Xml.XmlTextReaderImpl.ParseElementContent()
   at System.Xml.XmlTextReaderImpl.Read()
   at System.Xml.Linq.XContainer.ReadContentFrom(XmlReader r)
   at System.Xml.Linq.XContainer.ReadContentFrom(XmlReader r, LoadOptions o)
   at System.Xml.Linq.XDocument.Load(XmlReader reader, LoadOptions options)
   at System.Xml.Linq.XDocument.Parse(String text, LoadOptions options)
   at ECMA2Yaml.ECMALoader.LoadType(FileItem typeFile)
   at ECMA2Yaml.ECMALoader.LoadTypes(String basePath, Namespace ns)

For more details, please refer to the build report.

Note: Your PR may contain errors or warnings or suggestions unrelated to the files you changed. This happens when external dependencies like GitHub alias, Microsoft alias, cross repo links are updated. Please use these instructions to resolve them.

For any questions, please:

• Try searching the learn.microsoft.com contributor guides
• Post your question in the Learn support channel

[learn-build-service-prod]

Learn Build status updates of commit 671b5ae:

⚠️ Validation status: warnings

File	Status	Preview URL	Details
xml/Microsoft.Extensions.DependencyInjection/ServiceCollectionHostedServiceExtensions.xml	⚠️Warning	View	Details

xml/Microsoft.Extensions.DependencyInjection/ServiceCollectionHostedServiceExtensions.xml

• Line 0, Column 0: [Warning: xref-not-found] Cross reference not found: 'Microsoft.Extensions.DependencyInjection.IServiceCollection.AddSingleton'.
• Line 0, Column 0: [Warning: xref-not-found] Cross reference not found: 'Microsoft.Extensions.DependencyInjection.IServiceCollection.AddSingleton'.

For more details, please refer to the build report.

Note: Your PR may contain errors or warnings or suggestions unrelated to the files you changed. This happens when external dependencies like GitHub alias, Microsoft alias, cross repo links are updated. Please use these instructions to resolve them.

For any questions, please:

• Try searching the learn.microsoft.com contributor guides
• Post your question in the Learn support channel

[learn-build-service-prod]

Learn Build status updates of commit da969a3:

⚠️ Validation status: warnings

File	Status	Preview URL	Details
xml/Microsoft.Extensions.DependencyInjection/ServiceCollectionHostedServiceExtensions.xml	⚠️Warning	View	Details

xml/Microsoft.Extensions.DependencyInjection/ServiceCollectionHostedServiceExtensions.xml

• Line 0, Column 0: [Warning: xref-not-found] Cross reference not found: 'Microsoft.Extensions.DependencyInjection.ServiceCollectionServiceExtensions.AddSingleton'.
• Line 0, Column 0: [Warning: xref-not-found] Cross reference not found: 'Microsoft.Extensions.DependencyInjection.ServiceCollectionServiceExtensions.AddSingleton'.

For more details, please refer to the build report.

Note: Your PR may contain errors or warnings or suggestions unrelated to the files you changed. This happens when external dependencies like GitHub alias, Microsoft alias, cross repo links are updated. Please use these instructions to resolve them.

For any questions, please:

• Try searching the learn.microsoft.com contributor guides
• Post your question in the Learn support channel

[learn-build-service-prod]

Learn Build status updates of commit 1bded2d:

❌ Validation status: errors

Please follow instructions here which may help to resolve issue.

File	Status	Preview URL	Details
	❌Error		Details
xml/Microsoft.Extensions.DependencyInjection/ServiceCollectionHostedServiceExtensions.xml	❌Error		Details

• Line 0, Column 0: [Error: ECMA2Yaml_File_LoadFailed] Failed to load 1 files, aborting...

xml/Microsoft.Extensions.DependencyInjection/ServiceCollectionHostedServiceExtensions.xml

• Line 0, Column 0: [Error: ECMA2Yaml_InternalError]

Intenal Several Error: System.Xml.XmlException: Unexpected end of file while parsing CDATA has occurred. Line 128, position 1.
   at System.Xml.XmlTextReaderImpl.Throw(Exception e)
   at System.Xml.XmlTextReaderImpl.Throw(String res, String arg)
   at System.Xml.XmlTextReaderImpl.ParseCDataOrComment(XmlNodeType type, Int32& outStartPos, Int32& outEndPos)
   at System.Xml.XmlTextReaderImpl.ParseCDataOrComment(XmlNodeType type)
   at System.Xml.XmlTextReaderImpl.ParseElementContent()
   at System.Xml.XmlTextReaderImpl.Read()
   at System.Xml.Linq.XContainer.ReadContentFrom(XmlReader r)
   at System.Xml.Linq.XContainer.ReadContentFrom(XmlReader r, LoadOptions o)
   at System.Xml.Linq.XDocument.Load(XmlReader reader, LoadOptions options)
   at System.Xml.Linq.XDocument.Parse(String text, LoadOptions options)
   at ECMA2Yaml.ECMALoader.LoadType(FileItem typeFile)
   at ECMA2Yaml.ECMALoader.LoadTypes(String basePath, Namespace ns)

For more details, please refer to the build report.

Note: Your PR may contain errors or warnings or suggestions unrelated to the files you changed. This happens when external dependencies like GitHub alias, Microsoft alias, cross repo links are updated. Please use these instructions to resolve them.

For any questions, please:

• Try searching the learn.microsoft.com contributor guides
• Post your question in the Learn support channel

[learn-build-service-prod]

Learn Build status updates of commit 34bfecf:

❌ Validation status: errors

Please follow instructions here which may help to resolve issue.

File	Status	Preview URL	Details
	❌Error		Details
xml/Microsoft.Extensions.DependencyInjection/ServiceCollectionHostedServiceExtensions.xml	❌Error		Details

• Line 0, Column 0: [Error: ECMA2Yaml_File_LoadFailed] Failed to load 1 files, aborting...

xml/Microsoft.Extensions.DependencyInjection/ServiceCollectionHostedServiceExtensions.xml

• Line 0, Column 0: [Error: ECMA2Yaml_InternalError]

Intenal Several Error: System.Xml.XmlException: Unexpected end of file while parsing CDATA has occurred. Line 128, position 1.
   at System.Xml.XmlTextReaderImpl.Throw(Exception e)
   at System.Xml.XmlTextReaderImpl.Throw(String res, String arg)
   at System.Xml.XmlTextReaderImpl.ParseCDataOrComment(XmlNodeType type, Int32& outStartPos, Int32& outEndPos)
   at System.Xml.XmlTextReaderImpl.ParseCDataOrComment(XmlNodeType type)
   at System.Xml.XmlTextReaderImpl.ParseElementContent()
   at System.Xml.XmlTextReaderImpl.Read()
   at System.Xml.Linq.XContainer.ReadContentFrom(XmlReader r)
   at System.Xml.Linq.XContainer.ReadContentFrom(XmlReader r, LoadOptions o)
   at System.Xml.Linq.XDocument.Load(XmlReader reader, LoadOptions options)
   at System.Xml.Linq.XDocument.Parse(String text, LoadOptions options)
   at ECMA2Yaml.ECMALoader.LoadType(FileItem typeFile)
   at ECMA2Yaml.ECMALoader.LoadTypes(String basePath, Namespace ns)

For more details, please refer to the build report.

Note: Your PR may contain errors or warnings or suggestions unrelated to the files you changed. This happens when external dependencies like GitHub alias, Microsoft alias, cross repo links are updated. Please use these instructions to resolve them.

For any questions, please:

• Try searching the learn.microsoft.com contributor guides
• Post your question in the Learn support channel

[learn-build-service-prod]

Learn Build status updates of commit 0b74fd7:

✅ Validation status: passed

File	Status	Preview URL	Details
xml/Microsoft.Extensions.DependencyInjection/ServiceCollectionHostedServiceExtensions.xml	✅Succeeded	View

For more details, please refer to the build report.

For any questions, please:

• Try searching the learn.microsoft.com contributor guides
• Post your question in the Learn support channel

[buyaa-n]

Thank you @MichaelDeutschCoding for the contribution and thank you @gewarren for review.

[MichaelDeutschCoding]

Thanks so much for correcting and finishing this for me.