Binding V1 fails to generate for nested unions with numbered leaves

    container foo {
        leaf bar {
            type union {
                type enumeration {
                    enum "foo";
                }
                type string {
                    length 2;
                }
                type union {
                    type enumeration {
                        enum bar;
                    }
                    type string {
                        length 1;
                    }
                }
            }
        }

        leaf bar1 {
            type union {
                type enumeration {
                    enum "foo";
                }
                type string {
                    length 2;
                }
                type union {
                    type enumeration {
                        enum bar;
                    }
                    type string {
                        length 1;
                    }
                }
            }
        }
    }

java.lang.IllegalArgumentException: This generated type already contains equal enclosing transfer object.
    at com.google.common.base.Preconditions.checkArgument(Preconditions.java:135)
    at org.opendaylight.mdsal.binding.model.util.generated.type.builder.AbstractGeneratedTypeBuilder.addEnclosingTransferObject(AbstractGeneratedTypeBuilder.java:107)
    at org.opendaylight.mdsal.binding.model.util.generated.type.builder.CodegenGeneratedTypeBuilder.addEnclosingTransferObject(CodegenGeneratedTypeBuilder.java:1)
    at java.util.ArrayList.forEach(ArrayList.java:1257)
    at org.opendaylight.mdsal.binding.generator.impl.AbstractTypeGenerator.addTOToTypeBuilder(AbstractTypeGenerator.java:1886)
    at org.opendaylight.mdsal.binding.generator.impl.AbstractTypeGenerator.resolveLeafSchemaNodeAsMethod(AbstractTypeGenerator.java:1284)
    at org.opendaylight.mdsal.binding.generator.impl.AbstractTypeGenerator.addSchemaNodeToBuilderAsMethod(AbstractTypeGenerator.java:1004)
    at org.opendaylight.mdsal.binding.generator.impl.AbstractTypeGenerator.resolveDataSchemaNodes(AbstractTypeGenerator.java:945)
    at org.opendaylight.mdsal.binding.generator.impl.AbstractTypeGenerator.containerToGenType(AbstractTypeGenerator.java:276)
    at org.opendaylight.mdsal.binding.generator.impl.AbstractTypeGenerator.addSchemaNodeToBuilderAsMethod(AbstractTypeGenerator.java:1008)
    at org.opendaylight.mdsal.binding.generator.impl.AbstractTypeGenerator.resolveDataSchemaNodes(AbstractTypeGenerator.java:945)
    at org.opendaylight.mdsal.binding.generator.impl.AbstractTypeGenerator.moduleToGenTypes(AbstractTypeGenerator.java:214)
    at org.opendaylight.mdsal.binding.generator.impl.AbstractTypeGenerator.<init>(AbstractTypeGenerator.java:175)
    at org.opendaylight.mdsal.binding.generator.impl.CodegenTypeGenerator.<init>(CodegenTypeGenerator.java:30)
    at org.opendaylight.mdsal.binding.generator.impl.BindingGeneratorImpl.generateTypes(BindingGeneratorImpl.java:55)
    at org.opendaylight.mdsal.binding.generator.api.BindingGenerator.generateTypes(BindingGenerator.java:30)
    at