Update ReachabilityMetadata.md and improve titles and required fields in json schemas

Author: dnestoro

docs/reference-manual/native-image/ReachabilityMetadata.md

@@ -61,7 +61,7 @@ Computing metadata in code can be achieved in two ways:
             return aClass;
         }
     }
-  ```
+    ```
 
   When metadata is computed in code, the dynamically accessed elements will be included into the native executable's heap only if that part of the heap is reachable through an enclosing method (for example, `ReflectiveAccess#fetchFoo`) or a static field (for example, `InitializedAtBuildTime.aClass`).
 
@@ -89,6 +89,8 @@ A condition is specified in the following way:
 An entry with a `typeReachable` condition is considered only when the fully-qualified class is reachable.
 Currently, we support only `typeReachable` as a condition.
 
+Find more examples of the configuration files in the [GraalVM Reachability Metadata repository](https://github.com/oracle/graalvm-reachability-metadata).
+
 ## Metadata Types
 
 Native Image accepts the following types of reachability metadata:
@@ -144,53 +146,9 @@ Integer.class.getMethod("parseInt", params2);
 
 ### Specifying Reflection Metadata in JSON
 
-Reflection metadata can be specified in the `reflect-config.json` file.
-The JSON file is an array of reflection entries:
-```json
-[
-    {
-        "condition": {
-            "typeReachable": "<condition-class>"
-        },
-        "name": "<class>",
-        "methods": [
-            {"name": "<methodName>", "parameterTypes": ["<param-one-type>"]}
-        ],
-        "queriedMethods": [
-            {"name": "<methodName>", "parameterTypes": ["<param-one-type>"]}
-        ],
-        "fields": [
-            {"name": "<fieldName>"}
-        ],
-        "allDeclaredMethods": true,
-        "allDeclaredFields": true,
-        "allDeclaredConstructors": true,
-        "allPublicMethods": true,
-        "allPublicFields": true,
-        "allPublicConstructors": true,
-        "queryAllDeclaredMethods": true,
-        "queryAllDeclaredConstructors": true,
-        "queryAllPublicMethods": true,
-        "queryAllPublicConstructors": true,
-        "unsafeAllocated": true
-    }
-]
-```
-
-The fields in a reflection entry have the following meaning:
- - `condition`: See [Conditional Metadata Entries](#specifying-metadata-with-json)
- - `name`: Name of the class that will be reflectively looked up. This property is mandatory.
- - `methods`: List class methods that can be looked up and executed reflectively.
- Each method is described by its name and a list of parameter types.
- The parameter types are fully qualified Java class names.
- - `queriedMethods`: List of class methods that can only be looked up.
- The description of each method is identical to the `methods` list.
- - `fields`: List of class fields that can be looked up, read, or modified.
- - `all<access>(Methods/Fields/Constructors)`: Registers all methods/fields/constructors for lookup. Methods and constructors can also be invoked.
- `<access>` refers to different ways of querying these members in Java and can be either `Declared` or `Public`.
- For more information, see `java.lang.Class.getDeclaredMethods()` and `java.lang.Class.getPublicMethods()`.
- - `queryAll<access>(Methods/Constructors)`: Registers all methods/constructors for lookup only.
- - `unsafeAllocated`: Allows objects of this class to be allocated using `Unsafe.allocateInstance`.
+Reflection metadata should be specified in a _reflect-config.json_ file and conform to the JSON schema defined in 
+[reflect-config-schema-v1.0.0.json](https://github.com/oracle/graal/blob/master/docs/reference-manual/native-image/assets/reflect-config-schema-v1.0.0.json).
+The schema also includes further details and explanations how this configuration works.
 
 ## Java Native Interface
 
@@ -213,8 +171,10 @@ The generated metadata entry for the above call would look like:
 It is not possible to specify JNI metadata in code.
 
 ### JNI Metadata in JSON
-Metadata for JNI is provided in `jni-config.json` files.
-The JSON schema of JNI metadata is identical to the [Reflection metadata schema](#specifying-reflection-metadata-in-json).
+
+JNI metadata should be specified in a _jni-config.json_ file and conform to the JSON schema defined in
+[jni-config-schema-v1.0.0.json](https://github.com/oracle/graal/blob/master/docs/reference-manual/native-image/assets/jni-config-schema-v1.0.0.json).
+The schema also includes further details and explanations how this configuration works.
 
 ## Resources and Resource Bundles
 Java is capable of accessing any resource on the application class path, or the module path for which the requesting code has permission to access.
@@ -241,42 +201,10 @@ class Example {
 ```
 
 ### Resource Metadata in JSON
-Metadata for resources is provided in `resource-config.json` files.
-```json
-{
-  "resources": {
-    "includes": [
-      {
-        "condition": {
-          "typeReachable": "<condition-class>" 
-        },
-        "pattern": ".*\\.txt"
-      }
-    ],
-    "excludes": [
-      {
-        "condition": {
-          "typeReachable": "<condition-class>"
-        },
-        "pattern": ".*\\.txt"
-      }
-    ]
-  },
-  "bundles": [
-    {
-      "condition": {
-        "typeReachable": "<condition-class>"
-      },
-      "name": "fully.qualified.bundle.name",
-      "locales": ["en", "de", "sk"]
-    }
-  ]
-}
-```
 
-Native Image will iterate over all resources and match their relative paths against the Java regex specified in `includes`.
-If the path matches the regex, the resource is included.
-The `excludes` statement instructs `native-image` to omit certain included resources that match the given `pattern`.
+Resource metadata should be specified in a _resource-config.json_ file and conform to the JSON schema defined in
+[resource-config-schema-v1.0.0.json](https://github.com/oracle/graal/blob/master/docs/reference-manual/native-image/assets/resource-config-schema-v1.0.0.json).
+The schema also includes further details and explanations how this configuration works.
 
 ## Dynamic Proxy
 
@@ -316,20 +244,10 @@ The following methods are evaluated at build time when called with constant argu
  - `java.lang.reflect.Proxy.newProxyInstance`
 
 ### Dynamic Proxy Metadata in JSON
-Metadata for dynamic proxies is provided in `proxy-config.json` files.
-```json
-[
-  {
-    "condition": {
-      "typeReachable": "<condition-class>"
-    },
-    "interfaces": [
-      "IA",
-      "IB"
-    ]
-  }
-]
-```
+
+Dynamic proxy metadata should be specified in a _proxy-config.json_ file and conform to the JSON schema defined in
+[proxy-config-schema-v1.0.0.json](https://github.com/oracle/graal/blob/master/docs/reference-manual/native-image/assets/proxy-config-schema-v1.0.0.json).
+The schema also includes further details and explanations how this configuration works.
 
 ## Serialization
 Java can serialize any class that implements the `Serializable` interface.
@@ -366,42 +284,10 @@ To create a custom constructor for serialization use:
 Proxy classes can only be registered for serialization via the JSON files. 
 
 ### Serialization Metadata in JSON
-Metadata for serialization is provided in `serialization-config.json` files.
-```json
-{
-  "types": [
-    {
-      "condition": {
-        "typeReachable": "<condition-class>"
-      },
-      "name": "<fully-qualified-class-name>",
-      "customTargetConstructorClass": "<custom-target-constructor-class>"
-    }
-  ],
-  "lambdaCapturingTypes": [
-    {
-      "condition": {
-        "typeReachable": "<condition-class>"
-      },
-      "name": "<fully-qualified-class-name>"
-    }
-  ],
- "proxies": [
-   {
-     "condition": {
-       "typeReachable": "<condition-class>"
-     },
-     "interfaces": ["<fully-qualified-interface-name-1>", "<fully-qualified-interface-name-n>"]
-   }
- ]
-}
-```
-
-Each entry in `types` enables serializing and deserializing objects of the class given by `name`.
 
-Each entry in `lambdaCapturingTypes` enables lambda serialization: all lambdas declared in the methods of the class given by `name` can be serialized and deserialized.
-
-Each entry in `proxies` enables the [Proxy](https://docs.oracle.com/javase/8/docs/technotes/guides/reflection/proxy.html) serialization by providing an interface list that a proxy implements.
+Serialization metadata should be specified in a _serialization-config.json_ file and conform to the JSON schema defined in
+[serialization-config-schema-v1.0.0.json](https://github.com/oracle/graal/blob/master/docs/reference-manual/native-image/assets/serialization-config-schema-v1.0.0.json).
+The schema also includes further details and explanations how this configuration works.
 
 ## Predefined Classes
 
@@ -418,22 +304,10 @@ At runtime, if there is an attempt to load a class with the same name and byteco
 It is not possible to specify predefined classes in code.
 
 ### Predefined Classes Metadata in JSON
-Metadata for predefined classes is provided in `predefined-classes-config.json` files.
-```json
-[
-  {
-    "type": "agent-extracted",
-    "classes": [
-      {
-        "hash": "<class-bytecodes-hash>",
-        "nameInfo": "<class-name"
-      }
-    ]
-  }
-]
-```
 
-The JSON schema is accompanied by the `agent-extracted-predefined-classes` directory that contains the bytecode of the listed classes.
+Predefined classes metadata should be specified in a _predefined-classes-config.json_ file and conform to the JSON schema defined in
+[predefined-classes-config-schema-v1.0.0.json](https://github.com/oracle/graal/blob/master/docs/reference-manual/native-image/assets/predefined-classes-config-schema-v1.0.0.json).
+The schema also includes further details and explanations how this configuration works.
 
 ### Further Reading