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/* Copyright (c) Microsoft Open Technologies, Inc. All Rights Reserved Apache 2.0 License 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. See the Apache Version 2.0 License for specific language governing permissions and limitations under the License. */ /** * MobileServiceTableBase.java */ package com.microsoft.windowsazure.mobileservices.table; import android.net.Uri; import android.util.Pair; import com.google.common.util.concurrent.FutureCallback; import com.google.common.util.concurrent.Futures; import com.google.common.util.concurrent.ListenableFuture; import com.google.common.util.concurrent.SettableFuture; import com.google.gson.JsonElement; import com.google.gson.JsonNull; import com.google.gson.JsonObject; import com.google.gson.JsonParser; import com.google.gson.JsonPrimitive; import com.google.gson.JsonSyntaxException; import com.google.gson.annotations.SerializedName; import com.microsoft.windowsazure.mobileservices.MobileServiceClient; import com.microsoft.windowsazure.mobileservices.MobileServiceException; import com.microsoft.windowsazure.mobileservices.MobileServiceFeatures; import com.microsoft.windowsazure.mobileservices.http.MobileServiceHttpClient; import com.microsoft.windowsazure.mobileservices.http.RequestAsyncTask; import com.microsoft.windowsazure.mobileservices.http.ServiceFilterRequest; import com.microsoft.windowsazure.mobileservices.http.ServiceFilterRequestImpl; import com.microsoft.windowsazure.mobileservices.http.ServiceFilterResponse; import org.apache.http.client.methods.HttpDelete; import java.lang.reflect.Field; import java.util.ArrayList; import java.util.EnumSet; import java.util.List; import java.util.Locale; import java.util.Map.Entry; import java.util.TreeMap; abstract class MobileServiceTableBase implements MobileServiceTableSystemPropertiesProvider { /** * Tables URI part */ public static final String TABLES_URL = "tables/"; /** * The string prefix used to indicate system properties */ protected static final String SystemPropertyPrefix = "__"; /** * The name of the _system query string parameter */ protected static final String SystemPropertiesQueryParameterName = "__systemproperties"; /** * The system property names with the correct prefix. */ protected static final TreeMap<String, MobileServiceSystemProperty> SystemPropertyNameToEnum; static { SystemPropertyNameToEnum = new TreeMap<String, MobileServiceSystemProperty>(String.CASE_INSENSITIVE_ORDER); SystemPropertyNameToEnum.put(getSystemPropertyString(MobileServiceSystemProperty.CreatedAt), MobileServiceSystemProperty.CreatedAt); SystemPropertyNameToEnum.put(getSystemPropertyString(MobileServiceSystemProperty.UpdatedAt), MobileServiceSystemProperty.UpdatedAt); SystemPropertyNameToEnum.put(getSystemPropertyString(MobileServiceSystemProperty.Version), MobileServiceSystemProperty.Version); SystemPropertyNameToEnum.put(getSystemPropertyString(MobileServiceSystemProperty.Deleted), MobileServiceSystemProperty.Deleted); } /** * The version system property as a string with the prefix. */ protected static final String VersionSystemPropertyName = getSystemPropertyString( MobileServiceSystemProperty.Version); protected static final List<String> IdProperties; static { IdProperties = new ArrayList<String>(); IdProperties.add("id"); IdProperties.add("iD"); IdProperties.add("Id"); IdProperties.add("ID"); } /** * The MobileServiceClient used to invoke table operations */ protected MobileServiceClient mClient; /** * The name of the represented table */ protected String mTableName; /** * The Mobile Service system properties to be included with items */ protected EnumSet<MobileServiceSystemProperty> mSystemProperties = EnumSet .noneOf(MobileServiceSystemProperty.class); /** * Features to be sent in telemetry headers for requests made by this table */ protected EnumSet<MobileServiceFeatures> mFeatures = EnumSet.noneOf(MobileServiceFeatures.class); /** * Constructor * * @param name The name of the represented table * @param client The MobileServiceClient used to invoke table operations */ public MobileServiceTableBase(String name, MobileServiceClient client) { if (name == null || name.toString().trim().length() == 0) { throw new IllegalArgumentException("Invalid Table Name"); } if (client == null) { throw new IllegalArgumentException("Invalid Mobile Service Client"); } mClient = client; mTableName = name; } /** * Removes all system properties (name start with '__') from the instance if * the instance is determined to have a string id and therefore be for table * that supports system properties. * * @param instance The instance to remove the system properties from. * @param version Set to the value of the version system property before it is * removed. * @return The instance with the system properties removed. */ protected static JsonObject removeSystemProperties(JsonObject instance) { boolean haveCloned = false; for (Entry<String, JsonElement> property : instance.entrySet()) { if (SystemPropertyNameToEnum.containsKey(property.getKey())) { // We don't want to alter the original JsonObject passed in by // the caller // so if we find a system property to remove, we have to clone // first if (!haveCloned) { instance = (JsonObject) new JsonParser().parse(instance.toString()); haveCloned = true; } instance.remove(property.getKey()); } } return instance; } /** * Gets the version system property. * * @param instance The instance to remove the system properties from. * @return The value of the version system property or null if none present. */ protected static String getVersionSystemProperty(JsonObject instance) { String version = null; for (Entry<String, JsonElement> property : instance.entrySet()) { if (property.getKey().equalsIgnoreCase(VersionSystemPropertyName) && !property.getValue().isJsonNull()) { version = property.getValue().getAsString(); } } return version; } /** * Gets a valid etag from a string value. Etags are surrounded by double * quotes and any internal quotes must be escaped with a '\'. * * @param value The value to create the etag from. * @return The etag. */ protected static String getEtagFromValue(String value) { // If the value has double quotes, they will need to be escaped. for (int i = 0; i < value.length(); i++) { if (value.charAt(i) == '"') { if (i == 0) { value = String.format("%s%s", "\\", value); } else if (value.charAt(i - 1) != '\\') { value = String.format("%s%s%s", value.substring(0, i), "\\", value.substring(i)); } } } // All etags are quoted; return String.format("\"%s\"", value); } /** * Gets a value from an etag. Etags are surrounded by double quotes and any * internal quotes must be escaped with a '\'. * * @param etag The etag to get the value from. * @return The value. */ protected static String getValueFromEtag(String etag) { int length = etag.length(); if (length > 1 && etag.charAt(0) == '\"' && etag.charAt(length - 1) == '\"') { etag = etag.substring(1, length - 1); } return etag.replace("\\\"", "\""); } /** * Gets the system properties header value from the * MobileServiceSystemProperties. * * @param properties The system properties to set in the system properties header. * @return The system properties header value. Returns null if properties is * null or empty. */ private static String getSystemPropertiesString(EnumSet<MobileServiceSystemProperty> properties) { if (properties == null || properties.isEmpty()) { return null; } if (properties.containsAll(EnumSet.allOf(MobileServiceSystemProperty.class))) { return "*"; } StringBuilder sb = new StringBuilder(); int i = 0; for (MobileServiceSystemProperty systemProperty : properties) { sb.append(getSystemPropertyString(systemProperty)); i++; if (i < properties.size()) { sb.append(","); } } return sb.toString(); } /** * Gets the system property header value from the * MobileServiceSystemProperty. * * @param systemProperty The system property to set in the system properties header. * @return The system property header value. */ private static String getSystemPropertyString(MobileServiceSystemProperty systemProperty) { String property = systemProperty.toString().trim(); char firstLetterAsLower = property.toLowerCase(Locale.getDefault()).charAt(0); return SystemPropertyPrefix + firstLetterAsLower + property.substring(1); } /** * Returns the system properties defined or annotated in the entity class * * @param clazz Target entity class * @return List of entities */ protected static <F> EnumSet<MobileServiceSystemProperty> getSystemProperties(Class<F> clazz) { EnumSet<MobileServiceSystemProperty> result = EnumSet.noneOf(MobileServiceSystemProperty.class); Class<?> idClazz = getIdPropertyClass(clazz); if (idClazz != null && !isIntegerClass(idClazz)) { // Search for system properties annotations, regardless case for (Field field : clazz.getDeclaredFields()) { SerializedName serializedName = field.getAnnotation(SerializedName.class); if (serializedName != null) { if (SystemPropertyNameToEnum.containsKey(serializedName.value())) { result.add(SystemPropertyNameToEnum.get(serializedName.value())); } } else { if (SystemPropertyNameToEnum.containsKey(field.getName())) { result.add(SystemPropertyNameToEnum.get(field.getName())); } } } } // Otherwise, return empty return result; } /** * Returns the id property class defined or annotated in the entity class * * @param clazz Target entity class * @return Property class */ protected static <F> Class<?> getIdPropertyClass(Class<F> clazz) { // Search for id properties annotations, regardless case for (Field field : clazz.getDeclaredFields()) { SerializedName serializedName = field.getAnnotation(SerializedName.class); if (serializedName != null) { if (IdProperties.contains(serializedName.value())) { return field.getType(); } } else { if (IdProperties.contains(field.getName())) { return field.getType(); } } } return null; } /** * Returns the id property class defined or annotated in the entity class * * @param clazz Target entity class * @return Property class */ protected static <F> boolean isIntegerClass(Class<F> clazz) { return clazz.equals(Integer.class) || clazz.equals(Long.class) || clazz.equals(int.class) || clazz.equals(long.class); } /** * Transforms a 412 and 409 response to respective exception type. * * @param exc the Throwable from the request */ protected static Throwable transformHttpException(Throwable exc) { if (exc instanceof MobileServiceException) { MobileServiceException msExcep = (MobileServiceException) exc; if (msExcep.getResponse() != null && msExcep.getResponse().getStatus() != null && (msExcep.getResponse().getStatus().getStatusCode() == 412 || msExcep.getResponse().getStatus().getStatusCode() == 409)) { if (msExcep.getResponse().getStatus().getStatusCode() == 412) { String content = msExcep.getResponse().getContent(); JsonObject serverEntity = null; if (content != null) { try { serverEntity = new JsonParser().parse(content).getAsJsonObject(); } catch (JsonSyntaxException ex) { } } return new MobileServicePreconditionFailedExceptionJson(msExcep, serverEntity); } if (msExcep.getResponse().getStatus().getStatusCode() == 409) { return new MobileServiceConflictExceptionJson(msExcep, null); } } } return exc; } /** * Adds a feature which will be sent in telemetry headers for all requests * made by this table * * @param feature The feature that will be sent in requests by this table */ public void addFeature(MobileServiceFeatures feature) { mFeatures.add(feature); } /** * Returns the name of the represented table */ public String getTableName() { return mTableName; } /** * Returns the set of enabled System Properties */ public EnumSet<MobileServiceSystemProperty> getSystemProperties() { return mSystemProperties; } /** * Sets the set of enabled System Properties */ public void setSystemProperties(EnumSet<MobileServiceSystemProperty> systemProperties) { this.mSystemProperties = systemProperties; } /** * Returns the client used for table operations */ protected MobileServiceClient getClient() { return mClient; } /** * Deletes an entity from a Mobile Service Table * * @param id The entity id to delete */ public ListenableFuture<Void> delete(Integer id) { return this.delete(id, (List<Pair<String, String>>) null); } /** * Deletes an entity from a Mobile Service Table * * @param id The entity id to delete * @param callback Callback to invoke when the operation is completed * @deprecated use {@link delete(Object elementOrId)} instead */ public void delete(Integer id, TableDeleteCallback callback) { this.delete(id.toString(), null, callback); } /** * Deletes an entity from a Mobile Service Table using a given id * * @param id The id of the entity to delete * @param parameters A list of user-defined parameters and values to include in the * request URI query string */ public ListenableFuture<Void> delete(Integer id, List<Pair<String, String>> parameters) { return delete(id.toString(), parameters); } /** * Deletes an entity from a Mobile Service Table * * @param id The entity id to delete */ public ListenableFuture<Void> delete(Long id) { return this.delete(id, (List<Pair<String, String>>) null); } /** * Deletes an entity from a Mobile Service Table * * @param id The entity id to delete * @param callback Callback to invoke when the operation is completed * @deprecated use {@link delete(Object elementOrId)} instead */ public void delete(Long id, TableDeleteCallback callback) { this.delete(id.toString(), null, callback); } /** * Deletes an entity from a Mobile Service Table using a given id * * @param id The id of the entity to delete * @param parameters A list of user-defined parameters and values to include in the * request URI query string */ public ListenableFuture<Void> delete(Long id, List<Pair<String, String>> parameters) { return delete(id.toString(), parameters); } /** * Deletes an entity from a Mobile Service Table * * @param id The entity id to delete */ public ListenableFuture<Void> delete(String id) { return this.delete(id, (List<Pair<String, String>>) null); } /** * Deletes an entity from a Mobile Service Table * * @param id The entity id to delete * @param callback Callback to invoke when the operation is completed * @deprecated use {@link delete(Object elementOrId)} instead */ public void delete(String id, TableDeleteCallback callback) { this.delete(id, null, callback); } /** * Deletes an entity from a Mobile Service Table using a given id * * @param id The id of the entity to delete * @param parameters A list of user-defined parameters and values to include in the * request URI query string */ public ListenableFuture<Void> delete(String id, List<Pair<String, String>> parameters) { validateId(id); // Create delete request ServiceFilterRequest delete; Uri.Builder uriBuilder = Uri.parse(mClient.getAppUrl().toString()).buildUpon(); uriBuilder.path(TABLES_URL); uriBuilder.appendPath(mTableName); uriBuilder.appendPath(id); EnumSet<MobileServiceFeatures> features = mFeatures.clone(); if (parameters != null && parameters.size() > 0) { features.add(MobileServiceFeatures.AdditionalQueryParameters); } parameters = addSystemProperties(mSystemProperties, parameters); if (parameters != null && parameters.size() > 0) { for (Pair<String, String> parameter : parameters) { uriBuilder.appendQueryParameter(parameter.first, parameter.second); } } final SettableFuture<Void> future = SettableFuture.create(); delete = new ServiceFilterRequestImpl(new HttpDelete(uriBuilder.build().toString()), mClient.getAndroidHttpClientFactory()); if (!features.isEmpty()) { delete.addHeader(MobileServiceHttpClient.X_ZUMO_FEATURES, MobileServiceFeatures.featuresToString(features)); } // Create AsyncTask to execute the request new RequestAsyncTask(delete, mClient.createConnection()) { @Override protected void onPostExecute(ServiceFilterResponse result) { if (mTaskException == null) { future.set(null); } else { future.setException(transformHttpException(mTaskException)); } } }.executeTask(); return future; } /** * Deletes an entity from a Mobile Service Table using a given id * * @param id The id of the entity to delete * @param parameters A list of user-defined parameters and values to include in the * request URI query string * @param callback Callback to invoke when the operation is completed * @deprecated use {@link delete(Object elementOrId, java.util.List< android.util.Pair<String, * String>> parameters)} instead */ public void delete(String id, List<Pair<String, String>> parameters, final TableDeleteCallback callback) { ListenableFuture<Void> deleteFuture = delete(id, parameters); Futures.addCallback(deleteFuture, new FutureCallback<Void>() { @Override public void onFailure(Throwable exception) { if (exception instanceof Exception) { callback.onCompleted((Exception) exception, MobileServiceException.getServiceResponse(exception)); } else { callback.onCompleted(new Exception(exception), MobileServiceException.getServiceResponse(exception)); } } @Override public void onSuccess(Void v) { callback.onCompleted(null, null); } }); } /** * Patches the original entity with the one returned in the response after * executing the operation * * @param originalEntity The original entity * @param newEntity The entity obtained after executing the operation * @return */ protected JsonObject patchOriginalEntityWithResponseEntity(JsonObject originalEntity, JsonObject newEntity) { // Patch the object to return with the new values JsonObject patchedEntityJson = (JsonObject) new JsonParser().parse(originalEntity.toString()); for (Entry<String, JsonElement> entry : newEntity.entrySet()) { patchedEntityJson.add(entry.getKey(), entry.getValue()); } return patchedEntityJson; } /** * Gets the id property from a given element * * @param elementOrId The element to use * @return The id of the element */ protected Object getObjectId(Object elementOrId) { if (elementOrId == null || (elementOrId instanceof JsonNull)) { throw new IllegalArgumentException("Element cannot be null"); } else if (isNumericType(elementOrId)) { return getNumericValue(elementOrId); } else if (isStringType(elementOrId)) { return getStringValue(elementOrId); } else { JsonObject jsonObject; if (elementOrId instanceof JsonObject) { jsonObject = (JsonObject) elementOrId; } else { jsonObject = mClient.getGsonBuilder().create().toJsonTree(elementOrId).getAsJsonObject(); } updateIdProperty(jsonObject); JsonElement idProperty = jsonObject.get("id"); if (idProperty == null || (idProperty instanceof JsonNull)) { throw new IllegalArgumentException("Element must contain id property"); } if (isNumericType(idProperty)) { return getNumericValue(idProperty); } else if (isStringType(idProperty)) { return getStringValue(idProperty); } else { throw new IllegalArgumentException("Invalid id type"); } } } /** * Updates the JsonObject to have an id property * * @param json the element to evaluate */ protected void updateIdProperty(final JsonObject json) throws IllegalArgumentException { for (Entry<String, JsonElement> entry : json.entrySet()) { String key = entry.getKey(); if (key.equalsIgnoreCase("id")) { JsonElement element = entry.getValue(); if (isValidTypeId(element)) { if (!key.equals("id")) { // force the id name to 'id', no matter the casing json.remove(key); // Create a new id property using the given property // name JsonPrimitive value = entry.getValue().getAsJsonPrimitive(); if (value.isNumber()) { json.addProperty("id", value.getAsLong()); } else { json.addProperty("id", value.getAsString()); } } return; } else { throw new IllegalArgumentException("The id must be numeric or string"); } } } } /** * Validates if the id property is numeric or string. * * @param element * @return */ protected boolean isValidTypeId(JsonElement element) { return isStringType(element) || isNumericType(element); } /** * Validates the id value from an Object on Lookup/Update/Delete action * * @param elementOrId The Object to validate */ protected void validateId(final Object elementOrId) { if (elementOrId == null || (elementOrId instanceof JsonNull)) { throw new IllegalArgumentException("Element or id cannot be null."); } else if (isStringType(elementOrId)) { String id = getStringValue(elementOrId); if (!isValidStringId(id) || isDefaultStringId(id)) { throw new IllegalArgumentException("The string id is invalid."); } } else if (isNumericType(elementOrId)) { long id = getNumericValue(elementOrId); if (!isValidNumericId(id) || isDefaultNumericId(id)) { throw new IllegalArgumentException("The numeric id is invalid."); } } else if (elementOrId instanceof JsonObject) { validateId((JsonObject) elementOrId); } else { validateId(mClient.getGsonBuilder().create().toJsonTree(elementOrId).getAsJsonObject()); } } /** * Validates the id property from a JsonObject on Lookup/Update/Delete * action * * @param element The JsonObject to validate */ protected Object validateId(final JsonObject element) { if (element == null) { throw new IllegalArgumentException("The entity cannot be null."); } else { updateIdProperty(element); if (element.has("id")) { JsonElement idElement = element.get("id"); if (isStringType(idElement)) { String id = getStringValue(idElement); if (!isValidStringId(id) || isDefaultStringId(id)) { throw new IllegalArgumentException( "The entity has an invalid string value on id property."); } return id; } else if (isNumericType(idElement)) { long id = getNumericValue(idElement); if (!isValidNumericId(id) || isDefaultNumericId(id)) { throw new IllegalArgumentException( "The entity has an invalid numeric value on id property."); } return id; } else { throw new IllegalArgumentException( "The entity must have a valid numeric or string id property."); } } else { throw new IllegalArgumentException( "You must specify an id property with a valid numeric or string value."); } } } /** * Validates if the object represents a string value. * * @param o * @return */ protected boolean isStringType(Object o) { boolean result = (o instanceof String); if (o instanceof JsonElement) { JsonElement json = (JsonElement) o; if (json.isJsonPrimitive()) { JsonPrimitive primitive = json.getAsJsonPrimitive(); result = primitive.isString(); } } return result; } /** * Returns the string value represented by the object. * * @param o * @return */ protected String getStringValue(Object o) { String result; if (o instanceof String) { result = (String) o; } else if (o instanceof JsonElement) { JsonElement json = (JsonElement) o; if (json.isJsonPrimitive()) { JsonPrimitive primitive = json.getAsJsonPrimitive(); if (primitive.isString()) { result = primitive.getAsString(); } else { throw new IllegalArgumentException("Object does not represent a string value."); } } else { throw new IllegalArgumentException("Object does not represent a string value."); } } else { throw new IllegalArgumentException("Object does not represent a string value."); } return result; } /** * Validates if the string id is valid. * * @param id * @return */ protected boolean isValidStringId(String id) { boolean result = isDefaultStringId(id); if (!result && id != null) { result = id.length() <= 255; result &= !containsControlCharacter(id); result &= !containsSpecialCharacter(id); result &= !id.equals("."); result &= !id.equals(".."); } return result; } /** * Validates if the string id is a default value. * * @param id * @return */ protected boolean isDefaultStringId(String id) { return (id == null) || (id.equals("")); } /** * Validates if a given string contains a control character. * * @param s * @return */ protected boolean containsControlCharacter(String s) { boolean result = false; final int length = s.length(); for (int offset = 0; offset < length;) { final int codepoint = s.codePointAt(offset); if (Character.isISOControl(codepoint)) { result = true; break; } offset += Character.charCount(codepoint); } return result; } /** * Validates if a given string contains any of the following special * characters: "(U+0022), +(U+002B), /(U+002F), ?(U+003F), \(U+005C), * `(U+0060) * * @param s * @return */ protected boolean containsSpecialCharacter(String s) { boolean result = false; final int length = s.length(); final int cpQuotationMark = 0x0022; final int cpPlusSign = 0x002B; final int cpSolidus = 0x002F; final int cpQuestionMark = 0x003F; final int cpReverseSolidus = 0x005C; final int cpGraveAccent = 0x0060; for (int offset = 0; offset < length;) { final int codepoint = s.codePointAt(offset); if (codepoint == cpQuotationMark || codepoint == cpPlusSign || codepoint == cpSolidus || codepoint == cpQuestionMark || codepoint == cpReverseSolidus || codepoint == cpGraveAccent) { result = true; break; } offset += Character.charCount(codepoint); } return result; } /** * Validates if the object represents a numeric value. * * @param o * @return */ protected boolean isNumericType(Object o) { boolean result = (o instanceof Integer) || (o instanceof Long); if (o instanceof JsonElement) { JsonElement json = (JsonElement) o; if (json.isJsonPrimitive()) { JsonPrimitive primitive = json.getAsJsonPrimitive(); result = primitive.isNumber(); } } return result; } /** * Returns the numeric value represented by the object. * * @param o * @return */ protected long getNumericValue(Object o) { long result; if (o instanceof Integer) { result = (Integer) o; } else if (o instanceof Long) { result = (Long) o; } else if (o instanceof JsonElement) { JsonElement json = (JsonElement) o; if (json.isJsonPrimitive()) { JsonPrimitive primitive = json.getAsJsonPrimitive(); if (primitive.isNumber()) { result = primitive.getAsLong(); } else { throw new IllegalArgumentException("Object does not represent a string value."); } } else { throw new IllegalArgumentException("Object does not represent a string value."); } } else { throw new IllegalArgumentException("Object does not represent a string value."); } return result; } /** * Validates if the numeric id is valid. * * @param id * @return */ protected boolean isValidNumericId(long id) { return isDefaultNumericId(id) || id > 0; } /** * Validates if the numeric id is a default value. * * @param id * @return */ protected boolean isDefaultNumericId(long id) { return (id == 0); } /** * Adds the tables requested system properties to the parameters collection. * * @param systemProperties The system properties to add. * @param parameters The parameters collection. * @return The parameters collection with any requested system properties * included. */ public List<Pair<String, String>> addSystemProperties(EnumSet<MobileServiceSystemProperty> systemProperties, List<Pair<String, String>> parameters) { boolean containsSystemProperties = false; List<Pair<String, String>> result = new ArrayList<Pair<String, String>>( parameters != null ? parameters.size() : 0); // Make sure we have a case-insensitive parameters list if (parameters != null) { for (Pair<String, String> parameter : parameters) { result.add(parameter); containsSystemProperties = containsSystemProperties || parameter.first.equalsIgnoreCase(SystemPropertiesQueryParameterName); } } // If there is already a user parameter for the system properties, just // use it if (!containsSystemProperties) { String systemPropertiesString = getSystemPropertiesString(systemProperties); if (systemPropertiesString != null) { result.add(new Pair<String, String>(SystemPropertiesQueryParameterName, systemPropertiesString)); } } return result; } }