Refactor JSONFormatterPdxToJsonConverter to handle missing type metadata in both PdxInstances and in JSON, which is required to reconstitute the Object.
Resolves gh-67.
This commit is contained in:
John Blum
@@ -17,22 +17,37 @@ package org.springframework.geode.data.json.converter.support;
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import java.util.Optional;
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import com.fasterxml.jackson.core.JsonProcessingException;
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import com.fasterxml.jackson.databind.JsonNode;
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import com.fasterxml.jackson.databind.ObjectMapper;
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import com.fasterxml.jackson.databind.node.ObjectNode;
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import org.apache.geode.pdx.JSONFormatter;
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import org.apache.geode.pdx.PdxInstance;
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import org.apache.geode.pdx.WritablePdxInstance;
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import org.springframework.dao.DataRetrievalFailureException;
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import org.springframework.geode.data.json.converter.ObjectToJsonConverter;
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import org.springframework.geode.pdx.PdxInstanceBuilder;
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import org.springframework.lang.NonNull;
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import org.springframework.lang.Nullable;
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import org.springframework.util.Assert;
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import org.springframework.util.StringUtils;
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/**
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* An {@link ObjectToJsonConverter} implementation using the Apache Geode {@link JSONFormatter} to convert
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* from a {@link PdxInstance} to a {@literal JSON} {@link String}.
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*
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* @author John Blum
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* @see com.fasterxml.jackson.databind.JsonNode
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* @see com.fasterxml.jackson.databind.ObjectMapper
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* @see com.fasterxml.jackson.databind.node.ObjectNode
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* @see org.apache.geode.pdx.JSONFormatter
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* @see org.apache.geode.pdx.PdxInstance
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* @see org.apache.geode.pdx.WritablePdxInstance
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* @see org.springframework.geode.data.json.converter.ObjectToJsonConverter
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* @see org.springframework.geode.data.json.converter.support.JacksonObjectToJsonConverter
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* @see org.springframework.geode.pdx.PdxInstanceBuilder
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* @since 1.3.0
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*/
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public class JSONFormatterPdxToJsonConverter extends JacksonObjectToJsonConverter {
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@@ -70,6 +85,165 @@ public class JSONFormatterPdxToJsonConverter extends JacksonObjectToJsonConverte
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* @see org.apache.geode.pdx.PdxInstance
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*/
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protected @NonNull String convertPdxToJson(@NonNull PdxInstance pdxInstance) {
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//return JSONFormatter.toJSON(pdxInstance);
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//return JSONFormatter.toJSON(decorate(pdxInstance));
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return decorate(pdxInstance, jsonFormatterToJson(pdxInstance));
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}
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@NonNull String jsonFormatterToJson(@NonNull PdxInstance pdxInstance) {
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return JSONFormatter.toJSON(pdxInstance);
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}
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/**
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* WARNING!!!
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*
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* First, this method might be less than optimal and could lead to PDX type explosion!
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*
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* Second, this {@code pdxInstance.createWriter().setField(AT_TYPE_METADATA_PROPERTY_NAME, className);} ...
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*
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* Throws:
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* org.apache.geode.pdx.PdxFieldDoesNotExistException: A field named @type does not exist on ...
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* PdxType[dsid=0,typenum=7232261,name=example.app.crm.model.Customer,fields=[id:long:identity:0:idx0(relativeOffset)=0:idx1(vlfOffsetIndex)=0, name:String:1:idx0(relativeOffset)=8:idx1(vlfOffsetIndex)=-1,]]
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* at org.apache.geode.pdx.internal.WritablePdxInstanceImpl.setField(WritablePdxInstanceImpl.java:119)
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* ...
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*
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* This code needs to create a {@literal new} {@link PdxInstance} from an existing {@link PdxInstance}
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* or add the new (PDX) field to the PDX type metadata using {@code PdxType.addField(:PdxField)} before
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* setting the new field on the {@link PdxInstance} using the {@link WritablePdxInstance}. Unfortunately,
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* {@code PdxType} is part of the internal API and updating and ditributing a {@code PdxType} is complicated,
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* requiring a Distributed Lock, among other responsibilities.
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*/
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@SuppressWarnings("unused")
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protected @NonNull PdxInstance decorate(@NonNull PdxInstance pdxInstance) {
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if (isMissingObjectTypeMetadata(pdxInstance)) {
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String pdxInstanceClassName = pdxInstance.getClassName();
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Assert.isTrue(hasValidClassName(pdxInstance), () ->
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String.format("Class name [%s] is required and cannot be equal to [%s]",
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pdxInstanceClassName, JSONFormatter.JSON_CLASSNAME));
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pdxInstance = newPdxInstanceBuilder()
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.copy(pdxInstance)
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.writeString(AT_TYPE_METADATA_PROPERTY_NAME, pdxInstanceClassName)
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.create();
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}
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return pdxInstance;
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}
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/**
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* Constructs a new instance of {@link PdxInstanceBuilder}.
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*
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* @return a new instance of {@link PdxInstanceBuilder}; never {@literal null}.
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* @see org.springframework.geode.pdx.PdxInstanceBuilder
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*/
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@NonNull PdxInstanceBuilder newPdxInstanceBuilder() {
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return PdxInstanceBuilder.create();
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}
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/**
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* Decorates the given {@link String JSON} to include the {@literal @type} metadata property in order to
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* indicate the type of the {@literal JSON} object, which is required for deserialization back to PDX.
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*
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* If an {@link JsonProcessingException} is thrown during this operation and if the {@link PdxInstance}
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* has a {@link #hasValidClassName(PdxInstance) valid class name}, then an attempt is made to serialize
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* the {@link PdxInstance#getObject() object instance} of the {@link PdxInstance} to {@link String JSON}
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* using Jackson's {@link ObjectMapper}.
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*
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* @param pdxInstance required {@link PdxInstance} from which the {@link String JSON} was serialized;
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* must not be {@literal null}.
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* @param json {@link String JSON} generated from the serialization of the {@link PdxInstance};
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* must not be {@literal null}.
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* @return the decorated {@link String JSON} including the {@literal @type} metadata property.
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* @throws DataRetrievalFailureException if {@link String JSON} cannot be decorated with type metadata
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* and the {@link PdxInstance} is not based on a valid {@link Class} type.
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* @see org.apache.geode.pdx.PdxInstance
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* @see #newObjectMapper(Object)
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* @see super#convert(Object)
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*/
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@SuppressWarnings("unused")
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protected @NonNull String decorate(@NonNull PdxInstance pdxInstance, @NonNull String json) {
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if (isDecorationRequired(pdxInstance, json)) {
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try {
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ObjectMapper objectMapper = newObjectMapper(json);
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JsonNode jsonNode = objectMapper.readTree(json);
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if (isMissingObjectTypeMetadata(jsonNode)) {
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((ObjectNode) jsonNode).put(AT_TYPE_METADATA_PROPERTY_NAME, pdxInstance.getClassName());
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json = objectMapper.writeValueAsString(jsonNode);
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}
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return json;
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}
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catch (JsonProcessingException cause) {
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if (hasValidClassName(pdxInstance)) {
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return convertObjectToJson(pdxInstance.getObject());
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}
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String message = String.format("Failed to parse JSON [%s]", json);
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throw new DataRetrievalFailureException(message, cause);
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}
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}
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return json;
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}
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/**
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* Null-safe method to determine whether the given {@link PdxInstance}
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* has a valid {@link Class#getName() Class Name}.
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*
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* @param pdxInstance {@link PdxInstance} to evaluate;
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* @return a boolean value indicating whether the {@link PdxInstance}
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* has a valid {@link Class#getName() Class Name}.
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* @see org.apache.geode.pdx.PdxInstance
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*/
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boolean hasValidClassName(@Nullable PdxInstance pdxInstance) {
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return Optional.ofNullable(pdxInstance)
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.map(PdxInstance::getClassName)
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.filter(StringUtils::hasText)
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.filter(className -> !JSONFormatter.JSON_CLASSNAME.equals(className))
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.isPresent();
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}
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private boolean isDecorationRequired(@Nullable PdxInstance pdxInstance, @Nullable String json) {
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return isMissingObjectTypeMetadata(pdxInstance) && isValidJson(json);
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}
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private boolean isMissingObjectTypeMetadata(@Nullable JsonNode node) {
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return isObjectNode(node) && !node.has(AT_TYPE_METADATA_PROPERTY_NAME);
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}
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private boolean isMissingObjectTypeMetadata(@Nullable PdxInstance pdxInstance) {
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return pdxInstance != null && !pdxInstance.hasField(AT_TYPE_METADATA_PROPERTY_NAME);
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}
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/**
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* Null-safe method to determine if the given {@link JsonNode} represents a valid {@link String JSON} object.
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*
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* @param node {@link JsonNode} to evaluate.
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* @return a boolean valued indicating whether the given {@link JsonNode} is a valid {@link ObjectNode}.
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* @see com.fasterxml.jackson.databind.node.ObjectNode
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* @see com.fasterxml.jackson.databind.JsonNode
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*/
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boolean isObjectNode(@Nullable JsonNode node) {
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return node != null && (node.isObject() || node instanceof ObjectNode);
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}
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/**
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* Null-safe method to determine whether the given {@link String JSON} is valid.
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*
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* @param json {@link String} containing JSON to evaluate.
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* @return a boolean value indicating whether the given {@link String JSON} is valid.
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*/
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boolean isValidJson(@Nullable String json) {
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return StringUtils.hasText(json);
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}
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}
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