Update description of JVM identification and Special initialization c…

…onditions (#256)

src/documentation/articles/usage.md

@@ -9,7 +9,7 @@ KNet accepts many command-line switches to customize its behavior. The full list
 
 ### JVM identification
 
-One of the most important command-line switch is **JVMPath** and it is available in [JCOBridge switches](https://www.jcobridge.com/net-examples/command-line-options/): it can be used to set-up the location of the JVM library if JCOBridge is not able to identify a suitable JRE installation.
+One of the most important command-line switch is **JVMPath** and it is available in [JCOBridge switches](https://www.jcobridge.com/net-examples/command-line-options/): it can be used to set-up the location of the JVM library if JCOBridge is not able to identify a suitable JRE/JDK installation.
 If a developer is using KNet within its own product it is possible to override the **JVMPath** property with a snippet like the following one:
 
 ```c#
@@ -26,6 +26,27 @@ If a developer is using KNet within its own product it is possible to override t
     }
 ```
 
+**IMPORTANT NOTE**: `pathToJVM` shall be escaped
+1. `string pathToJVM = "C:\\Program Files\\Eclipse Adoptium\\jdk-11.0.18.10-hotspot\\bin\\server\\jvm.dll";`
+2. `string pathToJVM = @"C:\Program Files\Eclipse Adoptium\jdk-11.0.18.10-hotspot\bin\server\jvm.dll";`
+
+
+### Special initialization conditions
+
+[JCOBridge](https://www.jcobridge.com/) try to identify a suitable JRE/JDK installation within the system using some standard mechanism of JRE/JDK: `JAVA_HOME` environment variable or Windows registry if available.
+However it is possible, on Windows operating systems, that the library raises an **InvalidOperationException: Missing Java Key in registry: Couldn't find Java installed on the machine**.
+This means that neither `JAVA_HOME` nor Windows registry contains information about a default installed JRE/JDK: some vendors may not setup them.
+If the developer/user encounter this condition can do the following steps:
+1. On a command prompt execute `set | findstr JAVA_HOME` and verify the result;
+2. If something was reported maybe the `JAVA_HOME` environment variable is not set at system level, but at a different level like user level which is not visible from the KNet process that raised the exception;
+3. Try to set `JAVA_HOME` at system level e.g. `JAVA_HOME=C:\Program Files\Eclipse Adoptium\jdk-11.0.18.10-hotspot\`;
+4. Try to set `JCOBRIDGE_JVMPath` at system level e.g. `JCOBRIDGE_JVMPath=C:\Program Files\Eclipse Adoptium\jdk-11.0.18.10-hotspot\`.
+
+**IMPORTANT NOTES**:
+- One of `JCOBRIDGE_JVMPath` or `JAVA_HOME` environment variables or Windows registry (on Windows OSes) shall be available
+- `JCOBRIDGE_JVMPath` environment variable takes precedence over `JAVA_HOME` and Windows registry: you can set `JCOBRIDGE_JVMPath` to `C:\Program Files\Eclipse Adoptium\jdk-11.0.18.10-hotspot\bin\server\jvm.dll` and avoid to override `JVMPath` in your code
+- After first initialization steps, `JVMPath` takes precedence over `JCOBRIDGE_JVMPath`/`JAVA_HOME` environment variables or Windows registry
+
 ## Producer example
 
 Below the reader can found two different version of producer examples.