Proposed change to the Maven Plugin: Auto References (#3439)

* Added a new ReferenceFinder component for artifacts (per-type).  Added a proposed change to the maven plugin to auto detect refs

* Added a ref finder for JSON Schema

schema-util/asyncapi/src/main/java/io/apicurio/registry/content/refs/AsyncApiReferenceFinder.java

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+/*
+ * Copyright 2023 Red Hat Inc
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.apicurio.registry.content.refs;
+
+/**
+ * OpenAPI implementation of a reference finder.  Parses the OpenAPI document, finds all $refs, converts them
+ * to external references, and returns them.
+ * @author [email protected]
+ */
+public class AsyncApiReferenceFinder extends AbstractDataModelsReferenceFinder {
+
+}

schema-util/avro/src/main/java/io/apicurio/registry/content/refs/AvroReferenceFinder.java

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+/*
+ * Copyright 2023 Red Hat Inc
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.apicurio.registry.content.refs;
+
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.node.ArrayNode;
+
+import io.apicurio.registry.content.ContentHandle;
+
+/**
+ * An Apache Avro implementation of a reference finder.
+ * @author [email protected]
+ */
+public class AvroReferenceFinder implements ReferenceFinder {
+
+    private static final ObjectMapper mapper = new ObjectMapper();
+    private static final Logger log = LoggerFactory.getLogger(AvroReferenceFinder.class);
+
+    private static final Set<String> PRIMITIVE_TYPES = Set.of("null", "boolean", "int", "long", "float", "double",  "bytes", "string");
+
+    /**
+     * @see io.apicurio.registry.content.refs.ReferenceFinder#findExternalReferences(io.apicurio.registry.content.ContentHandle)
+     */
+    @Override
+    public Set<ExternalReference> findExternalReferences(ContentHandle content) {
+        try {
+            JsonNode tree = mapper.readTree(content.content());
+            Set<String> externalTypes = new HashSet<>();
+            findExternalTypesIn(tree, externalTypes);
+            return externalTypes.stream().map(type -> new ExternalReference(type)).collect(Collectors.toSet());
+        } catch (Exception e) {
+            log.error("Error finding external references in an Avro file.", e);
+            return Collections.emptySet();
+        }
+    }
+
+    private static void findExternalTypesIn(JsonNode schema, Set<String> externalTypes) {
+        // Null check
+        if (schema == null || schema.isNull()) {
+            return;
+        }
+
+        // Handle primitive/external types
+        if (schema.isTextual()) {
+            String type = schema.asText();
+            if (!PRIMITIVE_TYPES.contains(type)) {
+                externalTypes.add(type);
+            }
+        }
+
+        // Handle unions
+        if (schema.isArray()) {
+            ArrayNode schemas = (ArrayNode) schema;
+            schemas.forEach(s -> findExternalTypesIn(s, externalTypes));
+        }
+
+        // Handle records
+        if (schema.isObject() && schema.has("type") && !schema.get("type").isNull() && schema.get("type").asText().equals("record")) {
+            JsonNode fieldsNode = schema.get("fields");
+            if (fieldsNode != null && fieldsNode.isArray()) {
+                ArrayNode fields = (ArrayNode) fieldsNode;
+                fields.forEach(fieldNode -> {
+                    if (fieldNode.isObject()) {
+                        JsonNode typeNode = fieldNode.get("type");
+                        findExternalTypesIn(typeNode, externalTypes);
+                    }
+                });
+            }
+        }
+        // Handle arrays
+        if (schema.has("type") && !schema.get("type").isNull() && schema.get("type").asText().equals("array")) {
+            JsonNode items = schema.get("items");
+            findExternalTypesIn(items, externalTypes);
+        }
+        // Handle maps
+        if (schema.has("type") && !schema.get("type").isNull() && schema.get("type").asText().equals("map")) {
+            JsonNode values = schema.get("values");
+            findExternalTypesIn(values, externalTypes);
+        }
+    }
+
+}

schema-util/common/src/main/java/io/apicurio/registry/content/refs/ExternalReference.java

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+/*
+ * Copyright 2023 Red Hat Inc
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.apicurio.registry.content.refs;
+
+import java.util.Objects;
+
+/**
+ * Models a reference from one artifact to another.  This represents the information found in the content
+ * of an artifact, and is very type-specific.  For example, a JSON schema reference might look like this:
+ * 
+ * <pre>
+ * {
+ *   "$ref" : "types/data-types.json#/$defs/FooType"
+ * }
+ * </pre>
+ * 
+ * In this case, the fields of this type will be:
+ * 
+ * <ul>
+ *   <li><em>fullReference</em>: <code>types/data-types.json#/$defs/FooType</code></li>
+ *   <li><em>resource</em>: <code>types/data-types.json</code></li>
+ *   <li><em>component</em>: <code>#/$defs/FooType</code></li>
+ * </ul>
+ *
+ * For an Avro artifact a reference might look like this:
+ * 
+ * <pre>
+ * {
+ *   "name": "exchange",
+ *   "type": "com.kubetrade.schema.common.Exchange"
+ * }
+ * </pre>
+ * 
+ * In this case, the fields of this type will be:
+ * 
+ * <ul>
+ *   <li><em>fullReference</em>: <code>com.kubetrade.schema.common.Exchange</code></li>
+ *   <li><em>resource</em>: <code>com.kubetrade.schema.common.Exchange</code></li>
+ *   <li><em>component</em>: <em>null</em></li>
+ * </ul>
+ * 
+ * @author [email protected]
+ */
+public class ExternalReference {
+
+    private String fullReference;
+    private String resource;
+    private String component;
+
+    /**
+     * Constructor.
+     * @param fullReference
+     * @param resource
+     * @param component
+     */
+    public ExternalReference(String fullReference, String resource, String component) {
+        this.fullReference = fullReference;
+        this.resource = resource;
+        this.component = component;
+    }
+
+    /**
+     * Constructor.  This variant is useful if there is no component part of an external reference.  In this
+     * case the full reference is also the resource (and the component is null).
+     * @param reference
+     */
+    public ExternalReference(String reference) {
+        this(reference, reference, null);
+    }
+
+    /**
+     * @return the fullReference
+     */
+    public String getFullReference() {
+        return fullReference;
+    }
+
+    /**
+     * @param fullReference the fullReference to set
+     */
+    public void setFullReference(String fullReference) {
+        this.fullReference = fullReference;
+    }
+
+    /**
+     * @return the resource
+     */
+    public String getResource() {
+        return resource;
+    }
+
+    /**
+     * @param resource the resource to set
+     */
+    public void setResource(String resource) {
+        this.resource = resource;
+    }
+
+    /**
+     * @return the component
+     */
+    public String getComponent() {
+        return component;
+    }
+
+    /**
+     * @param component the component to set
+     */
+    public void setComponent(String component) {
+        this.component = component;
+    }
+
+    /**
+     * @see java.lang.Object#hashCode()
+     */
+    @Override
+    public int hashCode() {
+        return Objects.hash(fullReference);
+    }
+
+    /**
+     * @see java.lang.Object#equals(java.lang.Object)
+     */
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj)
+            return true;
+        if (obj == null)
+            return false;
+        if (getClass() != obj.getClass())
+            return false;
+        ExternalReference other = (ExternalReference) obj;
+        return Objects.equals(fullReference, other.fullReference);
+    }
+
+}

schema-util/common/src/main/java/io/apicurio/registry/content/refs/JsonPointerExternalReference.java

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+/*
+ * Copyright 2023 Red Hat Inc
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.apicurio.registry.content.refs;
+
+/**
+ * @author [email protected]
+ */
+public class JsonPointerExternalReference extends ExternalReference {
+
+    /**
+     * Constructor.
+     * @param jsonPointer
+     */
+    public JsonPointerExternalReference(String jsonPointer) {
+        super(jsonPointer, resourceFrom(jsonPointer), componentFrom(jsonPointer));
+    }
+
+    private static String componentFrom(String jsonPointer) {
+        int idx = jsonPointer.indexOf('#');
+        if (idx == 0) {
+            return jsonPointer;
+        } else if (idx > 0) {
+            return jsonPointer.substring(idx);
+        } else {
+            return null;
+        }
+    }
+
+    private static String resourceFrom(String jsonPointer) {
+        int idx = jsonPointer.indexOf('#');
+        if (idx == 0) {
+            return null;
+        } else if (idx > 0) {
+            return jsonPointer.substring(0, idx);
+        } else {
+            return jsonPointer;
+        }
+    }
+
+}

schema-util/common/src/main/java/io/apicurio/registry/content/refs/NoOpReferenceFinder.java

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+/*
+ * Copyright 2023 Red Hat Inc
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.apicurio.registry.content.refs;
+
+import java.util.Collections;
+import java.util.Set;
+
+import io.apicurio.registry.content.ContentHandle;
+
+/**
+ * @author [email protected]
+ */
+public class NoOpReferenceFinder implements ReferenceFinder {
+
+    public static final ReferenceFinder INSTANCE = new NoOpReferenceFinder();
+
+    /**
+     * @see io.apicurio.registry.content.refs.ReferenceFinder#findExternalReferences(io.apicurio.registry.content.ContentHandle)
+     */
+    @Override
+    public Set<ExternalReference> findExternalReferences(ContentHandle content) {
+        return Collections.emptySet();
+    }
+
+}