Remove hashes that don't work with Maven Central

gradle.properties

@@ -1,3 +1,22 @@
+#
+# Copyright 2020 See AUTHORS file
+#
+# 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.
+#
+#
+
 org.gradle.caching=true
 org.gradle.parallel=true
 org.gradle.configureondemand=true
+# Workaround for Maven Central not supporting SHA256 and 512 hashes.
+systemProp.org.gradle.internal.publish.checksums.insecure=true